memcg, oom: no oom-kill for __GFP_RETRY_MAYFAIL
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Message ID 20190428235613.166330-1-shakeelb@google.com
State New
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Series
  • memcg, oom: no oom-kill for __GFP_RETRY_MAYFAIL
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Commit Message

Shakeel Butt April 28, 2019, 11:56 p.m. UTC
The documentation of __GFP_RETRY_MAYFAIL clearly mentioned that the
OOM killer will not be triggered and indeed the page alloc does not
invoke OOM killer for such allocations. However we do trigger memcg
OOM killer for __GFP_RETRY_MAYFAIL. Fix that.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
---
 mm/memcontrol.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Comments

Michal Hocko April 29, 2019, 12:22 p.m. UTC | #1
On Sun 28-04-19 16:56:13, Shakeel Butt wrote:
> The documentation of __GFP_RETRY_MAYFAIL clearly mentioned that the
> OOM killer will not be triggered and indeed the page alloc does not
> invoke OOM killer for such allocations. However we do trigger memcg
> OOM killer for __GFP_RETRY_MAYFAIL. Fix that.

An example of __GFP_RETRY_MAYFAIL memcg OOM report would be nice. I
thought we haven't been using that flag for memcg allocations yet.
But this is definitely good to have addressed.

> Signed-off-by: Shakeel Butt <shakeelb@google.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/memcontrol.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 2713b45ec3f0..99eca724ed3b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2294,7 +2294,6 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	unsigned long nr_reclaimed;
>  	bool may_swap = true;
>  	bool drained = false;
> -	bool oomed = false;
>  	enum oom_status oom_status;
>  
>  	if (mem_cgroup_is_root(memcg))
> @@ -2381,7 +2380,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	if (nr_retries--)
>  		goto retry;
>  
> -	if (gfp_mask & __GFP_RETRY_MAYFAIL && oomed)
> +	if (gfp_mask & __GFP_RETRY_MAYFAIL)
>  		goto nomem;
>  
>  	if (gfp_mask & __GFP_NOFAIL)
> @@ -2400,7 +2399,6 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	switch (oom_status) {
>  	case OOM_SUCCESS:
>  		nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
> -		oomed = true;
>  		goto retry;
>  	case OOM_FAILED:
>  		goto force;
> -- 
> 2.21.0.593.g511ec345e18-goog
>
Shakeel Butt April 29, 2019, 2:37 p.m. UTC | #2
On Mon, Apr 29, 2019 at 5:22 AM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Sun 28-04-19 16:56:13, Shakeel Butt wrote:
> > The documentation of __GFP_RETRY_MAYFAIL clearly mentioned that the
> > OOM killer will not be triggered and indeed the page alloc does not
> > invoke OOM killer for such allocations. However we do trigger memcg
> > OOM killer for __GFP_RETRY_MAYFAIL. Fix that.
>
> An example of __GFP_RETRY_MAYFAIL memcg OOM report would be nice. I
> thought we haven't been using that flag for memcg allocations yet.
> But this is definitely good to have addressed.

Actually I am planning to use it for memcg allocations (specifically
fsnotify allocations).

>
> > Signed-off-by: Shakeel Butt <shakeelb@google.com>
>
> Acked-by: Michal Hocko <mhocko@suse.com>

Thanks.

>
> > ---
> >  mm/memcontrol.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 2713b45ec3f0..99eca724ed3b 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -2294,7 +2294,6 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
> >       unsigned long nr_reclaimed;
> >       bool may_swap = true;
> >       bool drained = false;
> > -     bool oomed = false;
> >       enum oom_status oom_status;
> >
> >       if (mem_cgroup_is_root(memcg))
> > @@ -2381,7 +2380,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
> >       if (nr_retries--)
> >               goto retry;
> >
> > -     if (gfp_mask & __GFP_RETRY_MAYFAIL && oomed)
> > +     if (gfp_mask & __GFP_RETRY_MAYFAIL)
> >               goto nomem;
> >
> >       if (gfp_mask & __GFP_NOFAIL)
> > @@ -2400,7 +2399,6 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
> >       switch (oom_status) {
> >       case OOM_SUCCESS:
> >               nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
> > -             oomed = true;
> >               goto retry;
> >       case OOM_FAILED:
> >               goto force;
> > --
> > 2.21.0.593.g511ec345e18-goog
> >
>
> --
> Michal Hocko
> SUSE Labs
Michal Hocko April 29, 2019, 2:52 p.m. UTC | #3
On Mon 29-04-19 07:37:08, Shakeel Butt wrote:
> On Mon, Apr 29, 2019 at 5:22 AM Michal Hocko <mhocko@kernel.org> wrote:
> >
> > On Sun 28-04-19 16:56:13, Shakeel Butt wrote:
> > > The documentation of __GFP_RETRY_MAYFAIL clearly mentioned that the
> > > OOM killer will not be triggered and indeed the page alloc does not
> > > invoke OOM killer for such allocations. However we do trigger memcg
> > > OOM killer for __GFP_RETRY_MAYFAIL. Fix that.
> >
> > An example of __GFP_RETRY_MAYFAIL memcg OOM report would be nice. I
> > thought we haven't been using that flag for memcg allocations yet.
> > But this is definitely good to have addressed.
> 
> Actually I am planning to use it for memcg allocations (specifically
> fsnotify allocations).

OK, then articulate it in the changelog please.

> > > Signed-off-by: Shakeel Butt <shakeelb@google.com>
> >
> > Acked-by: Michal Hocko <mhocko@suse.com>

Patch
diff mbox series

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2713b45ec3f0..99eca724ed3b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2294,7 +2294,6 @@  static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	unsigned long nr_reclaimed;
 	bool may_swap = true;
 	bool drained = false;
-	bool oomed = false;
 	enum oom_status oom_status;
 
 	if (mem_cgroup_is_root(memcg))
@@ -2381,7 +2380,7 @@  static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	if (nr_retries--)
 		goto retry;
 
-	if (gfp_mask & __GFP_RETRY_MAYFAIL && oomed)
+	if (gfp_mask & __GFP_RETRY_MAYFAIL)
 		goto nomem;
 
 	if (gfp_mask & __GFP_NOFAIL)
@@ -2400,7 +2399,6 @@  static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	switch (oom_status) {
 	case OOM_SUCCESS:
 		nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
-		oomed = true;
 		goto retry;
 	case OOM_FAILED:
 		goto force;