[RFC 2/4] mm: replace TIF_MEMDIE checks by tsk_is_oom_victim

Michal Hocko
2016-09-01T09:51:55Z

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.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
kernel/cpuset.c | 9 +++++----
mm/memcontrol.c | 2 +-
mm/oom_kill.c | 4 ++--
3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index c7fd2778ed50..8e370d9d63ee 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -54,6 +54,7 @@
#include <linux/time64.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>
+#include <linux/oom.h>

#include <asm/uaccess.h>
#include <linux/atomic.h>
@@ -2487,12 +2488,12 @@ 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.
*
@@ -2515,7 +2516,7 @@ 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.
*/
@@ -2533,7 +2534,7 @@ 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 9ee178ba7b71..df58733ca48e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1899,7 +1899,7 @@ 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 b11977585c7b..e26529edcee3 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -477,7 +477,7 @@ 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 oom victim, selects new victim
* unmap_page_range # frees some memory
*/
mutex_lock(&oom_lock);
@@ -1078,7 +1078,7 @@ 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(tsk_is_oom_victim(current));
}

mutex_unlock(&oom_lock);
--
2.8.1