linux/arch/mips
Dmitry Adamushko c90e6fbb22 MIPS: Fix endless loop when processing signals for kernel tasks
The problem occurs [1] when a kernel-mode task returns from a system
call with a pending signal.

A real-life scenario is a child of 'khelper' returning from a failed
kernel_execve() in ____call_usermodehelper() [ kernel/kmod.c ].
kernel_execve() fails due to a pending SIGKILL, which is the result of
"kill -9 -1" (at least, busybox's init does it upon reboot).

The loop is as follows:

* syscall_exit_work:
 - work_pending:            // start_of_the_loop
 - work_notifysig:
   - do_notify_resume()
     - do_signal()
       - if (!user_mode(regs)) return;
 - resume_userspace         // TIF_SIGPENDING is still set
 - work_pending             // so we call work_pending => goto
                            // start_of_the_loop

More information can be found in another LKML thread:
http://www.serverphorums.com/read.php?12,457826

[1] The problem was also reproduced on !CONFIG_VM86 x86, and the
following fix was accepted.

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=29a2e2836ff9ea65a603c89df217f4198973a74f

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3571/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-12-05 19:59:00 +01:00
..
alchemy MIPS: Alchemy: Merge PB1100/1500 support into DB1000 code. 2012-10-11 11:11:20 +02:00
ar7 arch: Use eth_random_addr 2012-07-16 22:39:25 -07:00
ath79 MIPS: ath79: Fix CPU/DDR frequency calculation for SRIF PLLs 2012-10-01 11:37:15 +02:00
bcm47xx MIPS: BCM47xx: Fix BCMA_DRIVER_PCI_HOSTMODE config dependencies 2012-07-19 11:23:43 +02:00
bcm63xx Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2012-10-09 16:08:04 +09:00
boot MIPS: Alchemy: Single kernel for DB1200/1300/1550 2012-10-11 11:11:20 +02:00
cavium-octeon MIPS: Remove irqflags.h dependency from bitops.h 2012-11-09 10:59:10 +01:00
cobalt
configs MIPS: Alchemy: Merge PB1100/1500 support into DB1000 code. 2012-10-11 11:11:20 +02:00
dec MIPS: DEC: use IS_ENABLED() 2012-07-23 13:55:54 +01:00
emma Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
fw mips, arc: fix build failure 2012-11-16 14:33:04 -08:00
include MIPS: Avoid mcheck by flushing page range in huge_ptep_set_access_flags() 2012-12-04 16:57:54 +01:00
jazz
jz4740 MIPS: JZ4740: Forward declare struct uart_port in header. 2012-10-17 17:00:50 +02:00
kernel MIPS: Fix endless loop when processing signals for kernel tasks 2012-12-05 19:59:00 +01:00
lantiq Merge branch 'master' of git://dev.phrozen.org/mips-next into mips-for-linux-next 2012-10-05 15:56:28 +02:00
lasat Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
lib MIPS: Fix crash that occurs when function tracing is enabled 2012-11-23 18:44:38 +01:00
loongson MIPS: Loongson 2: Sort out clock managment. 2012-08-01 18:10:06 +02:00
loongson1 MIPS: Loongson 1: more clk support and add select HAVE_CLK 2012-08-01 17:59:23 +02:00
math-emu Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
mm MIPS: Avoid mcheck by flushing page range in huge_ptep_set_access_flags() 2012-12-04 16:57:54 +01:00
mti-malta MIPS: Malta: Fix interupt number of CBUS UART. 2012-11-13 14:50:15 +01:00
mti-sead3 MIPS: Add core files for MIPS SEAD-3 development platform. 2012-09-13 15:43:46 -05:00
netlogic MIPS: Netlogic: Add support for built in DTB 2012-08-22 23:46:37 +02:00
oprofile Merge branches 'next/generic', 'next/alchemy', 'next/bcm63xx', 'next/cavium', 'next/jz4740', 'next/lantiq', 'next/loongson1b' and 'next/netlogic' into mips-for-linux-next 2012-07-25 16:37:46 +02:00
pci MIPS: Malta: Fix section mismatch. 2012-10-11 11:14:12 +02:00
pmc-sierra PCI changes for the 3.6 merge window: 2012-07-24 16:17:07 -07:00
pnx833x MIPS: PNX833x: use IS_ENABLED() macro 2012-07-23 13:55:53 +01:00
pnx8550
power
powertv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-07-24 10:01:50 -07:00
rb532 - More robust parsing especially of xattr data in JFFS2 2012-06-01 16:55:42 -07:00
sgi-ip22 Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
sgi-ip27 mips: zero out pg_data_t when it's allocated 2012-07-31 18:42:49 -07:00
sgi-ip32 Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
sibyte documentation: remove references to cpu_*_map. 2012-03-29 15:38:31 +10:30
sni MIPS: SNI: Switch RM400 serial to SCCNXP driver 2012-10-11 11:14:13 +02:00
txx9 MIPS: txx9: Fix redefinition of clk_* by adding select HAVE_CLK 2012-08-01 17:59:15 +02:00
vr41xx Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
wrppmc
Kbuild
Kbuild.platforms Merge branch 'ralf-3.7' of git://git.linux-mips.org/pub/scm/sjhill/linux-sjhill into mips-for-linux-next 2012-09-28 16:29:55 +02:00
Kconfig Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2012-10-14 14:39:05 -07:00
Kconfig.debug Fix typo in various Kconfig file 2012-04-16 14:40:08 +02:00
Makefile kbuild: Fix gcc -x syntax 2012-10-03 09:03:24 +02:00