linux/mm/oom_kill.c

471 lines
12 KiB
C
Raw Normal View History

/*
* linux/mm/oom_kill.c
*
* Copyright (C) 1998,2000 Rik van Riel
* Thanks go out to Claus Fischer for some serious inspiration and
* for goading me into coding this file...
*
* The routines in this file are used to kill a process when
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
* we're seriously out of memory. This gets called from __alloc_pages()
* in mm/page_alloc.c when we really run out of memory.
*
* Since we won't call these routines often (on a well-configured
* machine) this file will double as a 'coding guide' and a signpost
* for newbie kernel hackers. It features several pointers to major
* kernel subsystems and hints as to where to find out what things do.
*/
#include <linux/oom.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/swap.h>
#include <linux/timex.h>
#include <linux/jiffies.h>
#include <linux/cpuset.h>
#include <linux/module.h>
#include <linux/notifier.h>
int sysctl_panic_on_oom;
/* #define DEBUG */
/**
* badness - calculate a numeric value for how bad this task has been
* @p: task struct of which task we should calculate
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
* @uptime: current uptime in seconds
*
* The formula used is relatively simple and documented inline in the
* function. The main rationale is that we want to select a good task
* to kill when we run out of memory.
*
* Good in this context means that:
* 1) we lose the minimum amount of work done
* 2) we recover a large amount of memory
* 3) we don't kill anything innocent of eating tons of memory
* 4) we want to kill the minimum amount of processes (one)
* 5) we try to kill the process the user expects us to kill, this
* algorithm has been meticulously tuned to meet the principle
* of least surprise ... (be careful when you change it)
*/
unsigned long badness(struct task_struct *p, unsigned long uptime)
{
unsigned long points, cpu_time, run_time, s;
struct mm_struct *mm;
struct task_struct *child;
task_lock(p);
mm = p->mm;
if (!mm) {
task_unlock(p);
return 0;
}
/*
* The memory size of the process is the basis for the badness.
*/
points = mm->total_vm;
/*
* After this unlock we can no longer dereference local variable `mm'
*/
task_unlock(p);
/*
* swapoff can easily use up all memory, so kill those first.
*/
if (p->flags & PF_SWAPOFF)
return ULONG_MAX;
/*
* Processes which fork a lot of child processes are likely
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
* a good choice. We add half the vmsize of the children if they
* have an own mm. This prevents forking servers to flood the
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
* machine with an endless amount of children. In case a single
* child is eating the vast majority of memory, adding only half
* to the parents will make the child our kill candidate of choice.
*/
list_for_each_entry(child, &p->children, sibling) {
task_lock(child);
if (child->mm != mm && child->mm)
points += child->mm->total_vm/2 + 1;
task_unlock(child);
}
/*
* CPU time is in tens of seconds and run time is in thousands
* of seconds. There is no particular reason for this other than
* that it turned out to work very well in practice.
*/
cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
>> (SHIFT_HZ + 3);
if (uptime >= p->start_time.tv_sec)
run_time = (uptime - p->start_time.tv_sec) >> 10;
else
run_time = 0;
s = int_sqrt(cpu_time);
if (s)
points /= s;
s = int_sqrt(int_sqrt(run_time));
if (s)
points /= s;
/*
* Niced processes are most likely less important, so double
* their badness points.
*/
if (task_nice(p) > 0)
points *= 2;
/*
* Superuser processes are usually more important, so we make it
* less likely that we kill those.
*/
if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_ADMIN) ||
p->uid == 0 || p->euid == 0)
points /= 4;
/*
* We don't want to kill a process with direct hardware access.
* Not only could that mess up the hardware, but usually users
* tend to only have this flag set on applications they think
* of as important.
*/
if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
points /= 4;
/*
* If p's nodes don't overlap ours, it may still help to kill p
* because p may have allocated or otherwise mapped memory on
* this node before. However it will be less likely.
*/
if (!cpuset_excl_nodes_overlap(p))
points /= 8;
/*
* Adjust the score by oomkilladj.
*/
if (p->oomkilladj) {
if (p->oomkilladj > 0) {
if (!points)
points = 1;
points <<= p->oomkilladj;
} else
points >>= -(p->oomkilladj);
}
#ifdef DEBUG
printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n",
p->pid, p->comm, points);
#endif
return points;
}
/*
* Types of limitations to the nodes from which allocations may occur
*/
#define CONSTRAINT_NONE 1
#define CONSTRAINT_MEMORY_POLICY 2
#define CONSTRAINT_CPUSET 3
/*
* Determine the type of allocation constraint.
*/
static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask)
{
#ifdef CONFIG_NUMA
struct zone **z;
nodemask_t nodes;
int node;
nodes_clear(nodes);
/* node has memory ? */
for_each_online_node(node)
if (NODE_DATA(node)->node_present_pages)
node_set(node, nodes);
for (z = zonelist->zones; *z; z++)
[PATCH] cpuset: rework cpuset_zone_allowed api Elaborate the API for calling cpuset_zone_allowed(), so that users have to explicitly choose between the two variants: cpuset_zone_allowed_hardwall() cpuset_zone_allowed_softwall() Until now, whether or not you got the hardwall flavor depended solely on whether or not you or'd in the __GFP_HARDWALL gfp flag to the gfp_mask argument. If you didn't specify __GFP_HARDWALL, you implicitly got the softwall version. Unfortunately, this meant that users would end up with the softwall version without thinking about it. Since only the softwall version might sleep, this led to bugs with possible sleeping in interrupt context on more than one occassion. The hardwall version requires that the current tasks mems_allowed allows the node of the specified zone (or that you're in interrupt or that __GFP_THISNODE is set or that you're on a one cpuset system.) The softwall version, depending on the gfp_mask, might allow a node if it was allowed in the nearest enclusing cpuset marked mem_exclusive (which requires taking the cpuset lock 'callback_mutex' to evaluate.) This patch removes the cpuset_zone_allowed() call, and forces the caller to explicitly choose between the hardwall and the softwall case. If the caller wants the gfp_mask to determine this choice, they should (1) be sure they can sleep or that __GFP_HARDWALL is set, and (2) invoke the cpuset_zone_allowed_softwall() routine. This adds another 100 or 200 bytes to the kernel text space, due to the few lines of nearly duplicate code at the top of both cpuset_zone_allowed_* routines. It should save a few instructions executed for the calls that turned into calls of cpuset_zone_allowed_hardwall, thanks to not having to set (before the call) then check (within the call) the __GFP_HARDWALL flag. For the most critical call, from get_page_from_freelist(), the same instructions are executed as before -- the old cpuset_zone_allowed() routine it used to call is the same code as the cpuset_zone_allowed_softwall() routine that it calls now. Not a perfect win, but seems worth it, to reduce this chance of hitting a sleeping with irq off complaint again. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 08:34:25 +00:00
if (cpuset_zone_allowed_softwall(*z, gfp_mask))
node_clear(zone_to_nid(*z), nodes);
else
return CONSTRAINT_CPUSET;
if (!nodes_empty(nodes))
return CONSTRAINT_MEMORY_POLICY;
#endif
return CONSTRAINT_NONE;
}
/*
* Simple selection loop. We chose the process with the highest
* number of 'points'. We expect the caller will lock the tasklist.
*
* (not docbooked, we don't want this one cluttering up the manual)
*/
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
static struct task_struct *select_bad_process(unsigned long *ppoints)
{
struct task_struct *g, *p;
struct task_struct *chosen = NULL;
struct timespec uptime;
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
*ppoints = 0;
do_posix_clock_monotonic_gettime(&uptime);
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
do_each_thread(g, p) {
unsigned long points;
/*
* skip kernel threads and tasks which have already released
* their mm.
*/
if (!p->mm)
continue;
/* skip the init task */
if (is_init(p))
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
continue;
/*
* This task already has access to memory reserves and is
* being killed. Don't allow any other task access to the
* memory reserve.
*
* Note: this may have a chance of deadlock if it gets
* blocked waiting for another task which itself is waiting
* for memory. Is there a better alternative?
*/
if (test_tsk_thread_flag(p, TIF_MEMDIE))
return ERR_PTR(-1UL);
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
/*
* This is in the process of releasing memory so wait for it
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
* to finish before killing some other task by mistake.
*
* However, if p is the current task, we allow the 'kill' to
* go ahead if it is exiting: this will simply set TIF_MEMDIE,
* which will allow it to gain access to memory reserves in
* the process of exiting and releasing its resources.
* Otherwise we could get an easy OOM deadlock.
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
*/
if (p->flags & PF_EXITING) {
if (p != current)
return ERR_PTR(-1UL);
chosen = p;
*ppoints = ULONG_MAX;
}
if (p->oomkilladj == OOM_DISABLE)
continue;
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
points = badness(p, uptime.tv_sec);
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
if (points > *ppoints || !chosen) {
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
chosen = p;
[PATCH] OOM kill: children accounting In the badness() calculation, there's currently this piece of code: /* * Processes which fork a lot of child processes are likely * a good choice. We add the vmsize of the children if they * have an own mm. This prevents forking servers to flood the * machine with an endless amount of children */ list_for_each(tsk, &p->children) { struct task_struct *chld; chld = list_entry(tsk, struct task_struct, sibling); if (chld->mm = p->mm && chld->mm) points += chld->mm->total_vm; } The intention is clear: If some server (apache) keeps spawning new children and we run OOM, we want to kill the father rather than picking a child. This -- to some degree -- also helps a bit with getting fork bombs under control, though I'd consider this a desirable side-effect rather than a feature. There's one problem with this: No matter how many or few children there are, if just one of them misbehaves, and all others (including the father) do everything right, we still always kill the whole family. This hits in real life; whether it's javascript in konqueror resulting in kdeinit (and thus the whole KDE session) being hit or just a classical server that spawns children. Sidenote: The killer does kill all direct children as well, not only the selected father, see oom_kill_process(). The idea in attached patch is that we do want to account the memory consumption of the (direct) children to the father -- however not fully. This maintains the property that fathers with too many children will still very likely be picked, whereas a single misbehaving child has the chance to be picked by the OOM killer. In the patch I account only half (rounded up) of the children's vm_size to the parent. This means that if one child eats more mem than the rest of the family, it will be picked, otherwise it's still the father and thus the whole family that gets selected. This is heuristics -- we could debate whether accounting for a fourth would be better than for half of it. Or -- if people would consider it worth the trouble -- make it a sysctl. For now I sticked to accounting for half, which should IMHO be a significant improvement. The patch does one more thing: As users tend to be irritated by the choice of killed processes (mainly because the children are killed first, despite some of them having a very low OOM score), I added some more output: The selected (father) process will be reported first and it's oom_score printed to syslog. Description: Only account for half of children's vm size in oom score calculation This should still give the parent enough point in case of fork bombs. If any child however has more than 50% of the vm size of all children together, it'll get a higher score and be elected. This patch also makes the kernel display the oom_score. Signed-off-by: Kurt Garloff <garloff@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-21 02:27:51 +00:00
*ppoints = points;
}
[PATCH] cpusets: oom_kill tweaks This patch series extends the use of the cpuset attribute 'mem_exclusive' to support cpuset configurations that: 1) allow GFP_KERNEL allocations to come from a potentially larger set of memory nodes than GFP_USER allocations, and 2) can constrain the oom killer to tasks running in cpusets in a specified subtree of the cpuset hierarchy. Here's an example usage scenario. For a few hours or more, a large NUMA system at a University is to be divided in two halves, with a bunch of student jobs running in half the system under some form of batch manager, and with a big research project running in the other half. Each of the student jobs is placed in a small cpuset, but should share the classic Unix time share facilities, such as buffered pages of files in /bin and /usr/lib. The big research project wants no interference whatsoever from the student jobs, and has highly tuned, unusual memory and i/o patterns that intend to make full use of all the main memory on the nodes available to it. In this example, we have two big sibling cpusets, one of which is further divided into a more dynamic set of child cpusets. We want kernel memory allocations constrained by the two big cpusets, and user allocations constrained by the smaller child cpusets where present. And we require that the oom killer not operate across the two halves of this system, or else the first time a student job runs amuck, the big research project will likely be first inline to get shot. Tweaking /proc/<pid>/oom_adj is not ideal -- if the big research project really does run amuck allocating memory, it should be shot, not some other task outside the research projects mem_exclusive cpuset. I propose to extend the use of the 'mem_exclusive' flag of cpusets to manage such scenarios. Let memory allocations for user space (GFP_USER) be constrained by a tasks current cpuset, but memory allocations for kernel space (GFP_KERNEL) by constrained by the nearest mem_exclusive ancestor of the current cpuset, even though kernel space allocations will still _prefer_ to remain within the current tasks cpuset, if memory is easily available. Let the oom killer be constrained to consider only tasks that are in overlapping mem_exclusive cpusets (it won't help much to kill a task that normally cannot allocate memory on any of the same nodes as the ones on which the current task can allocate.) The current constraints imposed on setting mem_exclusive are unchanged. A cpuset may only be mem_exclusive if its parent is also mem_exclusive, and a mem_exclusive cpuset may not overlap any of its siblings memory nodes. This patch was presented on linux-mm in early July 2005, though did not generate much feedback at that time. It has been built for a variety of arch's using cross tools, and built, booted and tested for function on SN2 (ia64). There are 4 patches in this set: 1) Some minor cleanup, and some improvements to the code layout of one routine to make subsequent patches cleaner. 2) Add another GFP flag - __GFP_HARDWALL. It marks memory requests for USER space, which are tightly confined by the current tasks cpuset. 3) Now memory requests (such as KERNEL) that not marked HARDWALL can if short on memory, look in the potentially larger pool of memory defined by the nearest mem_exclusive ancestor cpuset of the current tasks cpuset. 4) Finally, modify the oom killer to skip any task whose mem_exclusive cpuset doesn't overlap ours. Patch (1), the one time I looked on an SN2 (ia64) build, actually saved 32 bytes of kernel text space. Patch (2) has no affect on the size of kernel text space (it just adds a preprocessor flag). Patches (3) and (4) added about 600 bytes each of kernel text space, mostly in kernel/cpuset.c, which matters only if CONFIG_CPUSET is enabled. This patch: This patch applies a few comment and code cleanups to mm/oom_kill.c prior to applying a few small patches to improve cpuset management of memory placement. The comment changed in oom_kill.c was seriously misleading. The code layout change in select_bad_process() makes room for adding another condition on which a process can be spared the oom killer (see the subsequent cpuset_nodes_overlap patch for this addition). Also a couple typos and spellos that bugged me, while I was here. This patch should have no material affect. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:18:09 +00:00
} while_each_thread(g, p);
return chosen;
}
/**
* Send SIGKILL to the selected process irrespective of CAP_SYS_RAW_IO
* flag though it's unlikely that we select a process with CAP_SYS_RAW_IO
* set.
*/
static void __oom_kill_task(struct task_struct *p, int verbose)
{
if (is_init(p)) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill init!\n");
return;
}
if (!p->mm) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill an mm-less task!\n");
return;
}
if (verbose)
printk(KERN_ERR "Killed process %d (%s)\n", p->pid, p->comm);
/*
* We give our sacrificial lamb high priority and access to
* all the memory it needs. That way it should be able to
* exit() and clear out its resources quickly...
*/
p->time_slice = HZ;
set_tsk_thread_flag(p, TIF_MEMDIE);
force_sig(SIGKILL, p);
}
static int oom_kill_task(struct task_struct *p)
{
struct mm_struct *mm;
struct task_struct *g, *q;
mm = p->mm;
/* WARNING: mm may not be dereferenced since we did not obtain its
* value from get_task_mm(p). This is OK since all we need to do is
* compare mm to q->mm below.
*
* Furthermore, even if mm contains a non-NULL value, p->mm may
* change to NULL at any time since we do not hold task_lock(p).
* However, this is of no concern to us.
*/
if (mm == NULL)
return 1;
/*
* Don't kill the process if any threads are set to OOM_DISABLE
*/
do_each_thread(g, q) {
if (q->mm == mm && q->oomkilladj == OOM_DISABLE)
return 1;
} while_each_thread(g, q);
__oom_kill_task(p, 1);
/*
* kill all processes that share the ->mm (i.e. all threads),
* but are in a different thread group. Don't let them have access
* to memory reserves though, otherwise we might deplete all memory.
*/
do_each_thread(g, q) {
if (q->mm == mm && q->tgid != p->tgid)
force_sig(SIGKILL, q);
} while_each_thread(g, q);
return 0;
}
static int oom_kill_process(struct task_struct *p, unsigned long points,
const char *message)
{
struct task_struct *c;
struct list_head *tsk;
/*
* If the task is already exiting, don't alarm the sysadmin or kill
* its children or threads, just set TIF_MEMDIE so it can die quickly
*/
if (p->flags & PF_EXITING) {
__oom_kill_task(p, 0);
return 0;
}
printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
message, p->pid, p->comm, points);
/* Try to kill a child first */
list_for_each(tsk, &p->children) {
c = list_entry(tsk, struct task_struct, sibling);
if (c->mm == p->mm)
continue;
if (!oom_kill_task(c))
return 0;
}
return oom_kill_task(p);
}
static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
int register_oom_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&oom_notify_list, nb);
}
EXPORT_SYMBOL_GPL(register_oom_notifier);
int unregister_oom_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&oom_notify_list, nb);
}
EXPORT_SYMBOL_GPL(unregister_oom_notifier);
/**
* out_of_memory - kill the "best" process when we run out of memory
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
* OR try to be smart about which process to kill. Note that we
* don't have to be perfect here, we just have to be good.
*/
void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
{
struct task_struct *p;
unsigned long points = 0;
unsigned long freed = 0;
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
/* Got some memory back in the last second. */
return;
if (printk_ratelimit()) {
printk(KERN_WARNING "%s invoked oom-killer: "
"gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
current->comm, gfp_mask, order, current->oomkilladj);
dump_stack();
show_mem();
}
cpuset_lock();
read_lock(&tasklist_lock);
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
switch (constrained_alloc(zonelist, gfp_mask)) {
case CONSTRAINT_MEMORY_POLICY:
oom_kill_process(current, points,
"No available memory (MPOL_BIND)");
break;
case CONSTRAINT_CPUSET:
oom_kill_process(current, points,
"No available memory in cpuset");
break;
case CONSTRAINT_NONE:
if (sysctl_panic_on_oom)
panic("out of memory. panic_on_oom is selected\n");
retry:
/*
* Rambo mode: Shoot down a process and hope it solves whatever
* issues we may have.
*/
p = select_bad_process(&points);
if (PTR_ERR(p) == -1UL)
goto out;
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
read_unlock(&tasklist_lock);
cpuset_unlock();
panic("Out of memory and no killable processes...\n");
}
if (oom_kill_process(p, points, "Out of memory"))
goto retry;
break;
}
out:
read_unlock(&tasklist_lock);
cpuset_unlock();
/*
* Give "p" a good chance of killing itself before we
* retry to allocate memory unless "p" is current
*/
if (!test_thread_flag(TIF_MEMDIE))
schedule_timeout_uninterruptible(1);
}