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Subject[PATCH 2/2] mm: replace TIF_MEMDIE checks by tsk_is_oom_victim
Date
From: Michal Hocko <mhocko@suse.com>

TIF_MEMDIE is set only to the tasks whick were either directly selected
by the OOM killer or passed through mark_oom_victim from the allocator
path. tsk_is_oom_victim is more generic and allows to identify all tasks
(threads) which share the mm with the oom victim.

Please note that the freezer still needs to check TIF_MEMDIE because
we cannot thaw tasks which do not participage in oom_victims counting
otherwise a !TIF_MEMDIE task could interfere after oom_disbale returns.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
kernel/cgroup/cpuset.c | 8 ++++----
mm/memcontrol.c | 2 +-
mm/oom_kill.c | 2 +-
3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index ca8376e5008c..1cc53dff0d94 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2497,12 +2497,12 @@ 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 as an oom victim, 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.
* GFP_KERNEL allocations are not so marked, so can escape to the
* nearest enclosing hardwalled ancestor cpuset.
*
@@ -2525,7 +2525,7 @@ 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
+ * tsk_is_oom_victim - any node ok
* GFP_KERNEL - any node in enclosing hardwalled cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
*/
@@ -2543,7 +2543,7 @@ 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(tsk_is_oom_victim(current)))
return true;
if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
return false;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 544d47e5cbbd..86a48affb938 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1896,7 +1896,7 @@ 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(tsk_is_oom_victim(current) ||
fatal_signal_pending(current) ||
current->flags & PF_EXITING))
goto force;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c9f3569a76c7..65cc2f9aaa05 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -483,7 +483,7 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
* [...]
* out_of_memory
* select_bad_process
- * # no TIF_MEMDIE task selects new victim
+ * # no TIF_MEMDIE, selects new victim
* unmap_page_range # frees some memory
*/
mutex_lock(&oom_lock);
--
2.13.2
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