> Otoh, if we make do_coredump() interruptible (and we should do this
> in any case), then perhaps the TIF_MEMDIE+PF_COREDUMP is not really
> needed? Afaics we always send SIGKILL along with TIF_MEMDIE.
How is to make per-process oom flag + interruptible coredump?
this per-process oom flag can be used vmscan shortcut exiting too.
(IOW, It can help DavidR mmap_sem issue)
===========================================================
Subject: [PATCH] oom: Make coredump interruptible
If oom victim process is under core dumping, sending SIGKILL cause
no-op. Unfortunately, coredump need relatively much memory. It mean
OOM vs coredump can makes deadlock.
Then, coredump logic should check the task has received SIGKILL
from OOM.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 5 +++++
include/linux/sched.h | 3 +++
mm/oom_kill.c | 1 +
3 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 535e763..aa47979 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2038,6 +2038,11 @@ static int elf_core_dump(struct coredump_params *cprm)
page_cache_release(page);
} else
stop = !dump_seek(cprm->file, PAGE_SIZE);
+
+ /* Now, The process received OOM. Exit soon! */
+ if (current->signal->oom_victim)
+ stop = 1;
+
if (stop)
goto end_coredump;
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8485aa2..1c4fa86 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -544,6 +544,9 @@ struct signal_struct {
int notify_count;
struct task_struct *group_exit_task;
+ /* true mean the process is OOM-killer victim. */
+ bool oom_victim;
+
/* thread group stop support, overloads group_exit_code too */
int group_stop_count;
unsigned int flags; /* see SIGNAL_* flags below */
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f33a1b8..39e31bf 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -400,6 +400,7 @@ static int __oom_kill_process(struct task_struct *p, struct mem_cgroup *mem,
*/
p->rt.time_slice = HZ;
set_tsk_thread_flag(p, TIF_MEMDIE);
+ p->signal->oom_victim = true;
force_sig(SIGKILL, p);
--
1.6.5.2
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