linux/arch/blackfin/kernel
David Howells 8feae13110 NOMMU: Make VMAs per MM as for MMU-mode linux
Make VMAs per mm_struct as for MMU-mode linux.  This solves two problems:

 (1) In SYSV SHM where nattch for a segment does not reflect the number of
     shmat's (and forks) done.

 (2) In mmap() where the VMA's vm_mm is set to point to the parent mm by an
     exec'ing process when VM_EXECUTABLE is specified, regardless of the fact
     that a VMA might be shared and already have its vm_mm assigned to another
     process or a dead process.

A new struct (vm_region) is introduced to track a mapped region and to remember
the circumstances under which it may be shared and the vm_list_struct structure
is discarded as it's no longer required.

This patch makes the following additional changes:

 (1) Regions are now allocated with alloc_pages() rather than kmalloc() and
     with no recourse to __GFP_COMP, so the pages are not composite.  Instead,
     each page has a reference on it held by the region.  Anything else that is
     interested in such a page will have to get a reference on it to retain it.
     When the pages are released due to unmapping, each page is passed to
     put_page() and will be freed when the page usage count reaches zero.

 (2) Excess pages are trimmed after an allocation as the allocation must be
     made as a power-of-2 quantity of pages.

 (3) VMAs are added to the parent MM's R/B tree and mmap lists.  As an MM may
     end up with overlapping VMAs within the tree, the VMA struct address is
     appended to the sort key.

 (4) Non-anonymous VMAs are now added to the backing inode's prio list.

 (5) Holes may be punched in anonymous VMAs with munmap(), releasing parts of
     the backing region.  The VMA and region structs will be split if
     necessary.

 (6) sys_shmdt() only releases one attachment to a SYSV IPC shared memory
     segment instead of all the attachments at that addresss.  Multiple
     shmat()'s return the same address under NOMMU-mode instead of different
     virtual addresses as under MMU-mode.

 (7) Core dumping for ELF-FDPIC requires fewer exceptions for NOMMU-mode.

 (8) /proc/maps is now the global list of mapped regions, and may list bits
     that aren't actually mapped anywhere.

 (9) /proc/meminfo gains a line (tagged "MmapCopy") that indicates the amount
     of RAM currently allocated by mmap to hold mappable regions that can't be
     mapped directly.  These are copies of the backing device or file if not
     anonymous.

These changes make NOMMU mode more similar to MMU mode.  The downside is that
NOMMU mode requires some extra memory to track things over NOMMU without this
patch (VMAs are no longer shared, and there are now region structs).

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Mike Frysinger <vapier.adi@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
2009-01-08 12:04:47 +00:00
..
cplb-mpu Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
cplb-nompu Blackfin arch: Faster C implementation of no-MPU CPLB handler 2009-01-07 23:14:38 +08:00
asm-offsets.c Blackfin arch: SMP supporting patchset: Blackfin kernel and memory management code 2008-11-18 17:48:22 +08:00
bfin_dma_5xx.c Blackfin arch: push cache flushing up to dma_memcpy 2009-01-07 23:14:39 +08:00
bfin_gpio.c Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
bfin_ksyms.c Blackfin arch: smp patch cleanup from LKML review 2009-01-07 23:14:39 +08:00
cplbinfo.c Blackfin arch: Faster C implementation of no-MPU CPLB handler 2009-01-07 23:14:38 +08:00
dma-mapping.c [Blackfin] arch: __FUNCTION__ is gcc-specific, use __func__ 2008-04-23 09:39:01 +08:00
early_printk.c Blackfin arch: fix typo in early printk bit size processing 2009-01-07 23:14:39 +08:00
entry.S Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
fixed_code.S Blackfin arch: move fixed code into init section 2008-11-18 17:48:22 +08:00
flat.c Blackfin arch: cleanup warnings from checkpatch -- no functional changes 2007-07-12 22:58:21 +08:00
gptimers.c Blackfin arch: Cleanup no functional changes 2008-05-20 16:42:39 +08:00
init_task.c take init_fs to saner place 2008-12-31 18:07:42 -05:00
ipipe.c Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
irqchip.c Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
kgdb.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/blackfin-2.6 2009-01-07 12:00:25 -08:00
kgdb_test.c Blackfin arch: merge kgdb test code using common CONFIG_KGDB_TESTS 2009-01-07 23:14:39 +08:00
Makefile Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
mcount.S Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
module.c Blackfin arch: Remove all traces of the relocation stack 2009-01-07 23:14:39 +08:00
process.c Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
ptrace.c NOMMU: Make VMAs per MM as for MMU-mode linux 2009-01-08 12:04:47 +00:00
reboot.c Blackfin arch: SMP supporting patchset: Blackfin kernel and memory management code 2008-11-18 17:48:22 +08:00
setup.c Blackfin arch: rewrite get_sclk()/get_vco() 2009-01-07 23:14:39 +08:00
signal.c [Blackfin] arch: disable single stepping when delivering a signal 2008-05-07 11:41:26 +08:00
sys_bfin.c unified (weak) sys_pipe implementation 2008-05-03 13:50:33 -07:00
time-ts.c cpumask: convert struct clock_event_device to cpumask pointers. 2008-12-13 21:20:26 +10:30
time.c Blackfin arch: merge adeos blackfin part to arch/blackfin/ 2009-01-07 23:14:39 +08:00
traps.c NOMMU: Make VMAs per MM as for MMU-mode linux 2009-01-08 12:04:47 +00:00
vmlinux.lds.S Blackfin arch: fix bugs in linker script when using upstream binutils 2009-01-07 23:14:39 +08:00