Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core)

Michal Hocko
2016-06-24T15:06:46Z

On Fri 24-06-16 16:05:58, Michal Hocko wrote:
> On Thu 23-06-16 20:52:21, Oleg Nesterov wrote:
> > On 06/23, Linus Torvalds wrote:
> > >
> > > On Thu, Jun 23, 2016 at 10:03 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> > > >
> > > > Let me quote my previous email ;)
> > > >
> > > > And we can't free/nullify it when the parent/debuger reaps a zombie,
> > > > say, mark_oom_victim() expects that get_task_struct() protects
> > > > thread_info as well.
> > > >
> > > > probably we can fix all such users though...
> > >
> > > TIF_MEMDIE is indeed a potential problem, but I don't think
> > > mark_oom_victim() is actually problematic.
> > >
> > > mark_oom_victim() is called with either "current",
> >
> > This is no longer true in -mm tree.
> >
> > But I agree, this is fixable (and in fact I still hope TIF_MEMDIE will die,
> > at least in its current form).
>
> We can move the flag to the task_struct. There are still some bits left
> there. This would be trivial so that the oom usage doesn't stay in the
> way.

Here is the patch. I've found two bugs when the TIF_MEMDIE was checked
on current rather than the given task. I will separate them into their
own patches (was just too lazy for it now). If the approach looks
reasonable then I will repost next week.
---
From 1baaa1f8f9568f95d8feccb28cf1994f8ca0df9f Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Fri, 24 Jun 2016 16:46:18 +0200
Subject: [PATCH] mm, oom: move TIF_MEMDIE to the task_struct

There is an interest to drop thread_info->flags usage for further clean
ups. TIF_MEMDIE stands in the way so let's move it out of the
thread_info into the task_struct. We cannot use flags because the oom
killer will set it for !current task without any locking so let's add
task_struct::memdie. It has to be atomic because we need it to be
updated atomically.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
arch/alpha/include/asm/thread_info.h | 1 -
arch/arc/include/asm/thread_info.h | 2 --
arch/arm/include/asm/thread_info.h | 1 -
arch/arm64/include/asm/thread_info.h | 1 -
arch/avr32/include/asm/thread_info.h | 2 --
arch/blackfin/include/asm/thread_info.h | 1 -
arch/c6x/include/asm/thread_info.h | 1 -
arch/cris/include/asm/thread_info.h | 1 -
arch/frv/include/asm/thread_info.h | 1 -
arch/h8300/include/asm/thread_info.h | 1 -
arch/hexagon/include/asm/thread_info.h | 1 -
arch/ia64/include/asm/thread_info.h | 1 -
arch/m32r/include/asm/thread_info.h | 1 -
arch/m68k/include/asm/thread_info.h | 1 -
arch/metag/include/asm/thread_info.h | 1 -
arch/microblaze/include/asm/thread_info.h | 1 -
arch/mips/include/asm/thread_info.h | 1 -
arch/mn10300/include/asm/thread_info.h | 1 -
arch/nios2/include/asm/thread_info.h | 1 -
arch/openrisc/include/asm/thread_info.h | 1 -
arch/parisc/include/asm/thread_info.h | 1 -
arch/powerpc/include/asm/thread_info.h | 1 -
arch/s390/include/asm/thread_info.h | 1 -
arch/score/include/asm/thread_info.h | 1 -
arch/sh/include/asm/thread_info.h | 1 -
arch/sparc/include/asm/thread_info_32.h | 1 -
arch/sparc/include/asm/thread_info_64.h | 1 -
arch/tile/include/asm/thread_info.h | 2 --
arch/um/include/asm/thread_info.h | 2 --
arch/unicore32/include/asm/thread_info.h | 1 -
arch/x86/include/asm/thread_info.h | 1 -
arch/xtensa/include/asm/thread_info.h | 1 -
drivers/staging/android/lowmemorykiller.c | 2 +-
fs/ext4/mballoc.c | 2 +-
include/linux/sched.h | 2 ++
kernel/cpuset.c | 12 ++++++------
kernel/exit.c | 2 +-
kernel/freezer.c | 2 +-
mm/ksm.c | 4 ++--
mm/memcontrol.c | 2 +-
mm/oom_kill.c | 20 ++++++++++----------
mm/page_alloc.c | 6 +++---
42 files changed, 28 insertions(+), 62 deletions(-)

diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 32e920a83ae5..126eaaf6559d 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -65,7 +65,6 @@ register struct thread_info *__current_thread_info __asm__("$8");
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SYSCALL_AUDIT 4 /* syscall audit active */
#define TIF_DIE_IF_KERNEL 9 /* dik recursion lock */
-#define TIF_MEMDIE 13 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 14 /* idle is polling for TIF_NEED_RESCHED */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/arch/arc/include/asm/thread_info.h b/arch/arc/include/asm/thread_info.h
index 3af67455659a..46d1fc1a073d 100644
--- a/arch/arc/include/asm/thread_info.h
+++ b/arch/arc/include/asm/thread_info.h
@@ -88,14 +88,12 @@ static inline __attribute_const__ struct thread_info *current_thread_info(void)
#define TIF_SYSCALL_TRACE 15 /* syscall trace active */

/* true if poll_idle() is polling TIF_NEED_RESCHED */
-#define TIF_MEMDIE 16

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
-#define _TIF_MEMDIE (1<<TIF_MEMDIE)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 776757d1604a..6277e56f15fd 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -146,7 +146,6 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,

#define TIF_NOHZ 12 /* in adaptive nohz mode */
#define TIF_USING_IWMMXT 17
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 20

#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index abd64bd1f6d9..d78b3b2945a9 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -114,7 +114,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SYSCALL_AUDIT 9
#define TIF_SYSCALL_TRACEPOINT 10
#define TIF_SECCOMP 11
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_FREEZE 19
#define TIF_RESTORE_SIGMASK 20
#define TIF_SINGLESTEP 21
diff --git a/arch/avr32/include/asm/thread_info.h b/arch/avr32/include/asm/thread_info.h
index d4d3079541ea..680be13234ab 100644
--- a/arch/avr32/include/asm/thread_info.h
+++ b/arch/avr32/include/asm/thread_info.h
@@ -70,7 +70,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_BREAKPOINT 4 /* enter monitor mode on return */
#define TIF_SINGLE_STEP 5 /* single step in progress */
-#define TIF_MEMDIE 6 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 7 /* restore signal mask in do_signal */
#define TIF_CPU_GOING_TO_SLEEP 8 /* CPU is entering sleep 0 mode */
#define TIF_NOTIFY_RESUME 9 /* callback before returning to user */
@@ -82,7 +81,6 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_BREAKPOINT (1 << TIF_BREAKPOINT)
#define _TIF_SINGLE_STEP (1 << TIF_SINGLE_STEP)
-#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)

diff --git a/arch/blackfin/include/asm/thread_info.h b/arch/blackfin/include/asm/thread_info.h
index 2966b93850a1..a45ff075ab6a 100644
--- a/arch/blackfin/include/asm/thread_info.h
+++ b/arch/blackfin/include/asm/thread_info.h
@@ -79,7 +79,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
#define TIF_SIGPENDING 1 /* signal pending */
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
-#define TIF_MEMDIE 4 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
#define TIF_IRQ_SYNC 7 /* sync pipeline stage */
#define TIF_NOTIFY_RESUME 8 /* callback before returning to user */
diff --git a/arch/c6x/include/asm/thread_info.h b/arch/c6x/include/asm/thread_info.h
index acc70c135ab8..22ff7b03641d 100644
--- a/arch/c6x/include/asm/thread_info.h
+++ b/arch/c6x/include/asm/thread_info.h
@@ -89,7 +89,6 @@ struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */

-#define TIF_MEMDIE 17 /* OOM killer killed process */

#define TIF_WORK_MASK 0x00007FFE /* work on irq/exception return */
#define TIF_ALLWORK_MASK 0x00007FFF /* work on any return to u-space */
diff --git a/arch/cris/include/asm/thread_info.h b/arch/cris/include/asm/thread_info.h
index 4ead1b40d2d7..79ebddc22aa3 100644
--- a/arch/cris/include/asm/thread_info.h
+++ b/arch/cris/include/asm/thread_info.h
@@ -70,7 +70,6 @@ struct thread_info {
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
-#define TIF_MEMDIE 17 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/arch/frv/include/asm/thread_info.h b/arch/frv/include/asm/thread_info.h
index ccba3b6ce918..993930f59d8e 100644
--- a/arch/frv/include/asm/thread_info.h
+++ b/arch/frv/include/asm/thread_info.h
@@ -86,7 +86,6 @@ register struct thread_info *__current_thread_info asm("gr15");
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
-#define TIF_MEMDIE 7 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h
index b408fe660cf8..68c10bce921e 100644
--- a/arch/h8300/include/asm/thread_info.h
+++ b/arch/h8300/include/asm/thread_info.h
@@ -73,7 +73,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SIGPENDING 1 /* signal pending */
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_SINGLESTEP 3 /* singlestepping active */
-#define TIF_MEMDIE 4 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
#define TIF_NOTIFY_RESUME 6 /* callback before returning to user */
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
diff --git a/arch/hexagon/include/asm/thread_info.h b/arch/hexagon/include/asm/thread_info.h
index b80fe1db7b64..e55c7d0a1755 100644
--- a/arch/hexagon/include/asm/thread_info.h
+++ b/arch/hexagon/include/asm/thread_info.h
@@ -112,7 +112,6 @@ register struct thread_info *__current_thread_info asm(QUOTED_THREADINFO_REG);
#define TIF_SINGLESTEP 4 /* restore ss @ return to usr mode */
#define TIF_RESTORE_SIGMASK 6 /* restore sig mask in do_signal() */
/* true if poll_idle() is polling TIF_NEED_RESCHED */
-#define TIF_MEMDIE 17 /* OOM killer killed process */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/arch/ia64/include/asm/thread_info.h b/arch/ia64/include/asm/thread_info.h
index aa995b67c3f5..77064b1d188a 100644
--- a/arch/ia64/include/asm/thread_info.h
+++ b/arch/ia64/include/asm/thread_info.h
@@ -97,7 +97,6 @@ struct thread_info {
#define TIF_SYSCALL_AUDIT 3 /* syscall auditing active */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_NOTIFY_RESUME 6 /* resumption notification requested */
-#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
#define TIF_DB_DISABLED 19 /* debug trap disabled for fsyscall */
#define TIF_RESTORE_RSE 21 /* user RBS is newer than kernel RBS */
diff --git a/arch/m32r/include/asm/thread_info.h b/arch/m32r/include/asm/thread_info.h
index f630d9c30b28..bc54a574fad0 100644
--- a/arch/m32r/include/asm/thread_info.h
+++ b/arch/m32r/include/asm/thread_info.h
@@ -102,7 +102,6 @@ static inline unsigned int get_thread_fault_code(void)
#define TIF_NOTIFY_RESUME 5 /* callback before returning to user */
#define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal() */
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h
index cee13c2e5161..ed497d31ea5d 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -68,7 +68,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 7 /* rescheduling necessary */
#define TIF_DELAYED_TRACE 14 /* single step a syscall */
#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
-#define TIF_MEMDIE 16 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 18 /* restore signal mask in do_signal */

#endif /* _ASM_M68K_THREAD_INFO_H */
diff --git a/arch/metag/include/asm/thread_info.h b/arch/metag/include/asm/thread_info.h
index 32677cc278aa..c506e5a61714 100644
--- a/arch/metag/include/asm/thread_info.h
+++ b/arch/metag/include/asm/thread_info.h
@@ -111,7 +111,6 @@ static inline int kstack_end(void *addr)
#define TIF_SECCOMP 5 /* secure computing */
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#define TIF_NOTIFY_RESUME 7 /* callback before returning to user */
-#define TIF_MEMDIE 8 /* is terminating due to OOM killer */
#define TIF_SYSCALL_TRACEPOINT 9 /* syscall tracepoint instrumentation */

diff --git a/arch/microblaze/include/asm/thread_info.h b/arch/microblaze/include/asm/thread_info.h
index 383f387b4eee..281a365bec48 100644
--- a/arch/microblaze/include/asm/thread_info.h
+++ b/arch/microblaze/include/asm/thread_info.h
@@ -113,7 +113,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
/* restore singlestep on return to user mode */
#define TIF_SINGLESTEP 4
-#define TIF_MEMDIE 6 /* is terminating due to OOM killer */
#define TIF_SYSCALL_AUDIT 9 /* syscall auditing active */
#define TIF_SECCOMP 10 /* secure computing */

diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index e309d8fcb516..3dd906330867 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -102,7 +102,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_UPROBE 6 /* breakpointed or singlestepping */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_NOHZ 19 /* in adaptive nohz mode */
#define TIF_FIXADE 20 /* Fix address errors in software */
#define TIF_LOGADE 21 /* Log address errors to syslog */
diff --git a/arch/mn10300/include/asm/thread_info.h b/arch/mn10300/include/asm/thread_info.h
index 4861a78c7160..1dd24f251a98 100644
--- a/arch/mn10300/include/asm/thread_info.h
+++ b/arch/mn10300/include/asm/thread_info.h
@@ -145,7 +145,6 @@ void arch_release_thread_info(struct thread_info *ti);
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
-#define TIF_MEMDIE 17 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE +(1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME +(1 << TIF_NOTIFY_RESUME)
diff --git a/arch/nios2/include/asm/thread_info.h b/arch/nios2/include/asm/thread_info.h
index d69c338bd19c..bf7d38c1c6e2 100644
--- a/arch/nios2/include/asm/thread_info.h
+++ b/arch/nios2/include/asm/thread_info.h
@@ -86,7 +86,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NOTIFY_RESUME 1 /* resumption notification requested */
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
-#define TIF_MEMDIE 4 /* is terminating due to OOM killer */
#define TIF_SECCOMP 5 /* secure computing */
#define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
diff --git a/arch/openrisc/include/asm/thread_info.h b/arch/openrisc/include/asm/thread_info.h
index 6e619a79a401..7678a1b2dc64 100644
--- a/arch/openrisc/include/asm/thread_info.h
+++ b/arch/openrisc/include/asm/thread_info.h
@@ -108,7 +108,6 @@ register struct thread_info *current_thread_info_reg asm("r10");
#define TIF_RESTORE_SIGMASK 9
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling * TIF_NEED_RESCHED
*/
-#define TIF_MEMDIE 17

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/arch/parisc/include/asm/thread_info.h b/arch/parisc/include/asm/thread_info.h
index e96e693fd58c..bcebec0b9418 100644
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
@@ -48,7 +48,6 @@ struct thread_info {
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_POLLING_NRFLAG 3 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_32BIT 4 /* 32 bit binary */
-#define TIF_MEMDIE 5 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 6 /* restore saved signal mask */
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
#define TIF_NOTIFY_RESUME 8 /* callback before returning to user */
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 7efee4a3240b..d744fa455dd2 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -97,7 +97,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SYSCALL_TRACEPOINT 15 /* syscall tracepoint instrumentation */
#define TIF_EMULATE_STACK_STORE 16 /* Is an instruction emulation
for stack store? */
-#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
#if defined(CONFIG_PPC64)
#define TIF_ELF2ABI 18 /* function descriptors must die! */
#endif
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 2fffc2c27581..8fc2704dd263 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -79,7 +79,6 @@ void arch_release_task_struct(struct task_struct *tsk);
#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
#define TIF_UPROBE 7 /* breakpointed or single-stepping */
#define TIF_31BIT 16 /* 32bit process */
-#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 18 /* restore signal mask in do_signal() */
#define TIF_SINGLE_STEP 19 /* This task is single stepped */
#define TIF_BLOCK_STEP 20 /* This task is block stepped */
diff --git a/arch/score/include/asm/thread_info.h b/arch/score/include/asm/thread_info.h
index 7d9ffb15c477..f6e1cc89cef9 100644
--- a/arch/score/include/asm/thread_info.h
+++ b/arch/score/include/asm/thread_info.h
@@ -78,7 +78,6 @@ register struct thread_info *__current_thread_info __asm__("r28");
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_NOTIFY_RESUME 5 /* callback before returning to user */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
diff --git a/arch/sh/include/asm/thread_info.h b/arch/sh/include/asm/thread_info.h
index 2afa321157be..017f3993f384 100644
--- a/arch/sh/include/asm/thread_info.h
+++ b/arch/sh/include/asm/thread_info.h
@@ -117,7 +117,6 @@ extern void init_thread_xstate(void);
#define TIF_NOTIFY_RESUME 7 /* callback before returning to user */
#define TIF_SYSCALL_TRACEPOINT 8 /* for ftrace syscall instrumentation */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
-#define TIF_MEMDIE 18 /* is terminating due to OOM killer */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/arch/sparc/include/asm/thread_info_32.h b/arch/sparc/include/asm/thread_info_32.h
index 229475f0d7ce..bcf81999db0b 100644
--- a/arch/sparc/include/asm/thread_info_32.h
+++ b/arch/sparc/include/asm/thread_info_32.h
@@ -110,7 +110,6 @@ register struct thread_info *current_thread_info_reg asm("g6");
* this quantum (SMP) */
#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
* TIF_NEED_RESCHED */
-#define TIF_MEMDIE 10 /* is terminating due to OOM killer */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/arch/sparc/include/asm/thread_info_64.h b/arch/sparc/include/asm/thread_info_64.h
index bde59825d06c..63b3285b7d46 100644
--- a/arch/sparc/include/asm/thread_info_64.h
+++ b/arch/sparc/include/asm/thread_info_64.h
@@ -191,7 +191,6 @@ register struct thread_info *current_thread_info_reg asm("g6");
* an immediate value in instructions such as andcc.
*/
/* flag bit 12 is available */
-#define TIF_MEMDIE 13 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 14

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/arch/tile/include/asm/thread_info.h b/arch/tile/include/asm/thread_info.h
index 4b7cef9e94e0..734d53f4b435 100644
--- a/arch/tile/include/asm/thread_info.h
+++ b/arch/tile/include/asm/thread_info.h
@@ -121,7 +121,6 @@ extern void _cpu_idle(void);
#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
#define TIF_SECCOMP 6 /* secure computing */
-#define TIF_MEMDIE 7 /* OOM killer at work */
#define TIF_NOTIFY_RESUME 8 /* callback before returning to user */
#define TIF_SYSCALL_TRACEPOINT 9 /* syscall tracepoint instrumentation */
#define TIF_POLLING_NRFLAG 10 /* idle is polling for TIF_NEED_RESCHED */
@@ -134,7 +133,6 @@ extern void _cpu_idle(void);
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
-#define _TIF_MEMDIE (1<<TIF_MEMDIE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index 053baff03674..b13047eeaede 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -58,7 +58,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SIGPENDING 1 /* signal pending */
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_RESTART_BLOCK 4
-#define TIF_MEMDIE 5 /* is terminating due to OOM killer */
#define TIF_SYSCALL_AUDIT 6
#define TIF_RESTORE_SIGMASK 7
#define TIF_NOTIFY_RESUME 8
@@ -67,7 +66,6 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
-#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)

diff --git a/arch/unicore32/include/asm/thread_info.h b/arch/unicore32/include/asm/thread_info.h
index e79ad6d5b5b2..2487cf9dd41e 100644
--- a/arch/unicore32/include/asm/thread_info.h
+++ b/arch/unicore32/include/asm/thread_info.h
@@ -121,7 +121,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
#define TIF_SYSCALL_TRACE 8
-#define TIF_MEMDIE 18
#define TIF_RESTORE_SIGMASK 20

#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index ffae84df8a93..79a4b75e814c 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -101,7 +101,6 @@ struct thread_info {
#define TIF_IA32 17 /* IA32 compatibility process */
#define TIF_FORK 18 /* ret_from_fork */
#define TIF_NOHZ 19 /* in adaptive nohz mode */
-#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
diff --git a/arch/xtensa/include/asm/thread_info.h b/arch/xtensa/include/asm/thread_info.h
index 7be2400f745a..791a0a0b5827 100644
--- a/arch/xtensa/include/asm/thread_info.h
+++ b/arch/xtensa/include/asm/thread_info.h
@@ -108,7 +108,6 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SIGPENDING 1 /* signal pending */
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_SINGLESTEP 3 /* restore singlestep on return to user mode */
-#define TIF_MEMDIE 5 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#define TIF_NOTIFY_RESUME 7 /* callback before returning to user */
#define TIF_DB_DISABLED 8 /* debug trap disabled for syscall */
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 2509e5df7244..55d02f2376ab 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -131,7 +131,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
if (!p)
continue;

- if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
+ if (atomic_read(&p->memdie) &&
time_before_eq(jiffies, lowmem_deathpending_timeout)) {
task_unlock(p);
rcu_read_unlock();
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c1ab3ec30423..ddc12f571c50 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4815,7 +4815,7 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
#endif
trace_ext4_mballoc_free(sb, inode, block_group, bit, count_clusters);

- /* __GFP_NOFAIL: retry infinitely, ignore TIF_MEMDIE and memcg limit. */
+ /* __GFP_NOFAIL: retry infinitely, ignore memdie tasks and memcg limit. */
err = ext4_mb_load_buddy_gfp(sb, block_group, &e4b,
GFP_NOFS|__GFP_NOFAIL);
if (err)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6d81a1eb974a..4c91fc0c2e8e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1856,6 +1856,8 @@ struct task_struct {
unsigned long task_state_change;
#endif
int pagefault_disabled;
+ /* oom victim - give it access to memory reserves */
+ atomic_t memdie;
#ifdef CONFIG_MMU
struct task_struct *oom_reaper_list;
#endif
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 73e93e53884d..857fac0b973d 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1038,9 +1038,9 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
- if (unlikely(test_thread_flag(TIF_MEMDIE)))
+ if (unlikely(atomic_read(&tsk->memdie)))
return;
- if (current->flags & PF_EXITING) /* Let dying task have memory */
+ if (tsk->flags & PF_EXITING) /* Let dying task have memory */
return;

task_lock(tsk);
@@ -2496,12 +2496,12 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
* If we're in interrupt, yes, we can always allocate. If @node is set in
* current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
* node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
- * yes. If current has access to memory reserves due to TIF_MEMDIE, yes.
+ * yes. If current has access to memory reserves due to memdie, yes.
* Otherwise, no.
*
* GFP_USER allocations are marked with the __GFP_HARDWALL bit,
* and do not allow allocations outside the current tasks cpuset
- * unless the task has been OOM killed as is marked TIF_MEMDIE.
+ * unless the task has been OOM killed as is marked memdie.
* GFP_KERNEL allocations are not so marked, so can escape to the
* nearest enclosing hardwalled ancestor cpuset.
*
@@ -2524,7 +2524,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
* affect that:
* in_interrupt - any node ok (current task context irrelevant)
* GFP_ATOMIC - any node ok
- * TIF_MEMDIE - any node ok
+ * memdie - any node ok
* GFP_KERNEL - any node in enclosing hardwalled cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
*/
@@ -2542,7 +2542,7 @@ bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
* Allow tasks that have access to memory reserves because they have
* been OOM killed to get memory anywhere.
*/
- if (unlikely(test_thread_flag(TIF_MEMDIE)))
+ if (unlikely(atomic_read(&current->memdie)))
return true;
if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
return false;
diff --git a/kernel/exit.c b/kernel/exit.c
index 9e6e1356e6bb..8bfdda9bc99a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -434,7 +434,7 @@ static void exit_mm(struct task_struct *tsk)
task_unlock(tsk);
mm_update_next_owner(mm);
mmput(mm);
- if (test_thread_flag(TIF_MEMDIE))
+ if (atomic_read(&current->memdie))
exit_oom_victim(tsk);
}

diff --git a/kernel/freezer.c b/kernel/freezer.c
index a8900a3bc27a..e1bd9f2780fe 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -42,7 +42,7 @@ bool freezing_slow_path(struct task_struct *p)
if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
return false;

- if (test_thread_flag(TIF_MEMDIE))
+ if (atomic_read(&p->memdie))
return false;

if (pm_nosig_freezing || cgroup_freezing(p))
diff --git a/mm/ksm.c b/mm/ksm.c
index 73d43bafd9fb..8d5a295fb955 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -396,11 +396,11 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
*
* VM_FAULT_OOM: at the time of writing (late July 2009), setting
* aside mem_cgroup limits, VM_FAULT_OOM would only be set if the
- * current task has TIF_MEMDIE set, and will be OOM killed on return
+ * current task has memdie set, and will be OOM killed on return
* to user; and ksmd, having no mm, would never be chosen for that.
*
* But if the mm is in a limited mem_cgroup, then the fault may fail
- * with VM_FAULT_OOM even if the current task is not TIF_MEMDIE; and
+ * with VM_FAULT_OOM even if the current task is not memdie; and
* even ksmd can fail in this way - though it's usually breaking ksm
* just to undo a merge it made a moment before, so unlikely to oom.
*
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3e8f9e5e9291..df411de17a75 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1987,7 +1987,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
* bypass the last charges so that they can exit quickly and
* free their memory.
*/
- if (unlikely(test_thread_flag(TIF_MEMDIE) ||
+ if (unlikely(atomic_read(&current->memdie) ||
fatal_signal_pending(current) ||
current->flags & PF_EXITING))
goto force;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4c21f744daa6..9d24007cdb82 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -473,7 +473,7 @@ static bool __oom_reap_task(struct task_struct *tsk)
* [...]
* out_of_memory
* select_bad_process
- * # no TIF_MEMDIE task selects new victim
+ * # no memdie task selects new victim
* unmap_page_range # frees some memory
*/
mutex_lock(&oom_lock);
@@ -593,7 +593,7 @@ static void oom_reap_task(struct task_struct *tsk)
}

/*
- * Clear TIF_MEMDIE because the task shouldn't be sitting on a
+ * Clear memdie because the task shouldn't be sitting on a
* reasonably reclaimable memory anymore or it is not a good candidate
* for the oom victim right now because it cannot release its memory
* itself nor by the oom reaper.
@@ -669,14 +669,14 @@ void mark_oom_victim(struct task_struct *tsk)
{
WARN_ON(oom_killer_disabled);
/* OOM killer might race with memcg OOM */
- if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
+ if (!atomic_add_unless(&tsk->memdie, 1, 1))
return;
atomic_inc(&tsk->signal->oom_victims);
/*
* Make sure that the task is woken up from uninterruptible sleep
* if it is frozen because OOM killer wouldn't be able to free
* any memory and livelock. freezing_slow_path will tell the freezer
- * that TIF_MEMDIE tasks should be ignored.
+ * that memdie tasks should be ignored.
*/
__thaw_task(tsk);
atomic_inc(&oom_victims);
@@ -687,7 +687,7 @@ void mark_oom_victim(struct task_struct *tsk)
*/
void exit_oom_victim(struct task_struct *tsk)
{
- if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
+ if (!atomic_add_unless(&tsk->memdie, -1, 0))
return;
atomic_dec(&tsk->signal->oom_victims);

@@ -771,7 +771,7 @@ bool task_will_free_mem(struct task_struct *task)
* If the process has passed exit_mm we have to skip it because
* we have lost a link to other tasks sharing this mm, we do not
* have anything to reap and the task might then get stuck waiting
- * for parent as zombie and we do not want it to hold TIF_MEMDIE
+ * for parent as zombie and we do not want it to hold memdie
*/
p = find_lock_task_mm(task);
if (!p)
@@ -836,7 +836,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,

/*
* 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
+ * its children or threads, just set memdie so it can die quickly
*/
if (task_will_free_mem(p)) {
mark_oom_victim(p);
@@ -893,7 +893,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
mm = victim->mm;
atomic_inc(&mm->mm_count);
/*
- * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
+ * We should send SIGKILL before setting memdie in order to prevent
* the OOM victim from depleting the memory reserves from the user
* space under its control.
*/
@@ -1016,7 +1016,7 @@ bool out_of_memory(struct oom_control *oc)
* quickly exit and free its memory.
*
* But don't select if current has already released its mm and cleared
- * TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
+ * memdie flag at exit_mm(), otherwise an OOM livelock may occur.
*/
if (current->mm && task_will_free_mem(current)) {
mark_oom_victim(current);
@@ -1096,7 +1096,7 @@ void pagefault_out_of_memory(void)
* be a racing OOM victim for which oom_killer_disable()
* is waiting for.
*/
- WARN_ON(test_thread_flag(TIF_MEMDIE));
+ WARN_ON(atomic_read(&current->memdie));
}

mutex_unlock(&oom_lock);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 89128d64d662..6c550afde6a4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3050,7 +3050,7 @@ void warn_alloc_failed(gfp_t gfp_mask, unsigned int order, const char *fmt, ...)
* of allowed nodes.
*/
if (!(gfp_mask & __GFP_NOMEMALLOC))
- if (test_thread_flag(TIF_MEMDIE) ||
+ if (atomic_read(&current->memdie) ||
(current->flags & (PF_MEMALLOC | PF_EXITING)))
filter &= ~SHOW_MEM_FILTER_NODES;
if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
@@ -3428,7 +3428,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
alloc_flags |= ALLOC_NO_WATERMARKS;
else if (!in_interrupt() &&
((current->flags & PF_MEMALLOC) ||
- unlikely(test_thread_flag(TIF_MEMDIE))))
+ unlikely(atomic_read(&current->memdie))))
alloc_flags |= ALLOC_NO_WATERMARKS;
}
#ifdef CONFIG_CMA
@@ -3637,7 +3637,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
}

/* Avoid allocations with no watermarks from looping endlessly */
- if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
+ if (atomic_read(&current->memdie) && !(gfp_mask & __GFP_NOFAIL))
goto nopage;

/*
--
2.8.1

--
Michal Hocko
SUSE Labs