The patch titled
memrlimit fix sleep inside sleeplock in mm_update_next_owner()
has been added to the -mm tree. Its filename is
memrlimit-cgroup-mm-owner-callback-changes-to-add-task-info-memrlimit-fix-sleep-inside-sleeplock-in-mm_update_next_owner.patch
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------------------------------------------------------
Subject: memrlimit fix sleep inside sleeplock in mm_update_next_owner()
From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
We have a sleep inside a spinlock (read side locking of tasklist_lock). We
try to acquire mmap_sem without releasing the read_lock. Since we have
the task_struct of the new process, we can release the read_lock, before
acquiring the task_lock of the chosen one.
Reviewed-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Sudhir Kumar <skumar@xxxxxxxxxxxxxxxxxx>
Cc: YAMAMOTO Takashi <yamamoto@xxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Pavel Emelianov <xemul@xxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff -puN kernel/exit.c~memrlimit-cgroup-mm-owner-callback-changes-to-add-task-info-memrlimit-fix-sleep-inside-sleeplock-in-mm_update_next_owner kernel/exit.c
--- a/kernel/exit.c~memrlimit-cgroup-mm-owner-callback-changes-to-add-task-info-memrlimit-fix-sleep-inside-sleeplock-in-mm_update_next_owner
+++ a/kernel/exit.c
@@ -626,28 +626,24 @@ retry:
assign_new_owner:
BUG_ON(c == p);
get_task_struct(c);
+ read_unlock(&tasklist_lock);
down_write(&mm->mmap_sem);
/*
* The task_lock protects c->mm from changing.
* We always want mm->owner->mm == mm
*/
task_lock(c);
- /*
- * Delay read_unlock() till we have the task_lock()
- * to ensure that c does not slip away underneath us
- */
- read_unlock(&tasklist_lock);
if (c->mm != mm) {
task_unlock(c);
- put_task_struct(c);
up_write(&mm->mmap_sem);
+ put_task_struct(c);
goto retry;
}
cgroup_mm_owner_callbacks(mm->owner, c);
mm->owner = c;
task_unlock(c);
- put_task_struct(c);
up_write(&mm->mmap_sem);
+ put_task_struct(c);
}
#endif /* CONFIG_MM_OWNER */
_
Patches currently in -mm which might be from balbir@xxxxxxxxxxxxxxxxxx are
delay-accounting-maintainer-update.patch
cgroup-use-read-lock-to-guard-find_existing_css_set.patch
mark-res_counter_charge_locked-with-__must_check.patch
memcg-make-global-var-read_mostly.patch
memcg-avoid-unnecessary-initialization.patch
memcg-remove-refcnt-from-page_cgroup-fix-memcg-fix-mem_cgroup_end_migration-race.patch
memcg-clean-up-checking-of-the-disabled-flag.patch
memrlimit-add-memrlimit-controller-documentation.patch
memrlimit-setup-the-memrlimit-controller.patch
memrlimit-cgroup-mm-owner-callback-changes-to-add-task-info.patch
memrlimit-cgroup-mm-owner-callback-changes-to-add-task-info-memrlimit-fix-sleep-inside-sleeplock-in-mm_update_next_owner.patch
memrlimit-add-memrlimit-controller-accounting-and-control.patch
memrlimit-add-memrlimit-controller-accounting-and-control-fix.patch
memrlimit-improve-error-handling.patch
memrlimit-improve-error-handling-update.patch
memrlimit-handle-attach_task-failure-add-can_attach-callback.patch
memrlimit-handle-attach_task-failure-add-can_attach-callback-update.patch
distinct-tgid-tid-i-o-statistics.patch
per-task-delay-accounting-add-memory-reclaim-delay.patch
per-task-delay-accounting-update-document-and-getdelaysc-for-memory-reclaim.patch
gcov-architecture-specific-compile-flag-adjustments-x86_64-fix.patch
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