The patch titled
oom: introduce find_lock_task_mm to fix mm false positives fix
has been added to the -mm tree. Its filename is
oom-select-task-from-tasklist-for-mempolicy-ooms-introduce-find_lock_task_mm-to-fix-mm-false-positives-fix.patch
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------------------------------------------------------
Subject: oom: introduce find_lock_task_mm to fix mm false positives fix
From: David Rientjes <rientjes@xxxxxxxxxx>
find_lock_task_mm() should be documented so that we clearly understand
what it does and why we need it.
At the same time, remove a stale coment about dereferencing of a local
variable "mm" in badness() which no longer exists and was removed when
find_lock_task_mm() was added.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN mm/oom_kill.c~oom-select-task-from-tasklist-for-mempolicy-ooms-introduce-find_lock_task_mm-to-fix-mm-false-positives-fix mm/oom_kill.c
--- a/mm/oom_kill.c~oom-select-task-from-tasklist-for-mempolicy-ooms-introduce-find_lock_task_mm-to-fix-mm-false-positives-fix
+++ a/mm/oom_kill.c
@@ -81,6 +81,12 @@ static bool has_intersects_mems_allowed(
}
#endif /* CONFIG_NUMA */
+/*
+ * The process p may have detached its own ->mm while exiting or through
+ * use_mm(), but one or more of its subthreads may still have a valid
+ * pointer. Return p, or any of its subthreads with a valid ->mm, with
+ * task_lock() held.
+ */
static struct task_struct *find_lock_task_mm(struct task_struct *p)
{
struct task_struct *t = p;
@@ -135,10 +141,6 @@ unsigned long badness(struct task_struct
* The memory size of the process is the basis for the badness.
*/
points = p->mm->total_vm;
-
- /*
- * After this unlock we can no longer dereference local variable `mm'
- */
task_unlock(p);
/*
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
avr32-invoke-oom-killer-from-page-fault.patch
oom-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch
oom-pf_exiting-check-should-take-mm-into-account.patch
oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch
oom-dump_tasks-use-find_lock_task_mm-too.patch
oom-improve-commentary-in-dump_tasks.patch
oom-dump_tasks-use-find_lock_task_mm-too-dump_tasks-use-find_lock_task_mm-too-fix.patch
oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch
oom-avoid-sending-exiting-tasks-a-sigkill.patch
oom-filter-tasks-not-sharing-the-same-cpuset.patch
oom-sacrifice-child-with-highest-badness-score-for-parent.patch
oom-sacrifice-child-with-highest-badness-score-for-parent-protect-dereferencing-of-tasks-comm.patch
oom-sacrifice-child-with-highest-badness-score-for-parent-fix.patch
oom-select-task-from-tasklist-for-mempolicy-ooms.patch
oom-select-task-from-tasklist-for-mempolicy-ooms-add-has_intersects_mems_allowed-uma-variant.patch
oom-select-task-from-tasklist-for-mempolicy-ooms-introduce-find_lock_task_mm-to-fix-mm-false-positives-fix.patch
oom-enable-oom-tasklist-dump-by-default.patch
oom-avoid-oom-killer-for-lowmem-allocations.patch
oom-extract-panic-helper-function.patch
oom-remove-special-handling-for-pagefault-ooms.patch
oom-move-sysctl-declarations-to-oomh.patch
oom-remove-unnecessary-code-and-cleanup.patch
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