On Tue 22-11-16 07:29:36, Michal Hocko wrote:
> I would even go one step further and do the following because, honestly,
> I never liked GFP_NOFAIL having OOM side effects.
>
> @@ -3078,32 +3078,31 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
> if (page)
> goto out;
>
> - if (!(gfp_mask & __GFP_NOFAIL)) {
> - /* Coredumps can quickly deplete all memory reserves */
> - if (current->flags & PF_DUMPCORE)
> - goto out;
> - /* The OOM killer will not help higher order allocs */
> - if (order > PAGE_ALLOC_COSTLY_ORDER)
> - goto out;
> - /* The OOM killer does not needlessly kill tasks for lowmem */
> - if (ac->high_zoneidx < ZONE_NORMAL)
> - goto out;
> - if (pm_suspended_storage())
> - goto out;
> - /*
> - * XXX: GFP_NOFS allocations should rather fail than rely on
> - * other request to make a forward progress.
> - * We are in an unfortunate situation where out_of_memory cannot
> - * do much for this context but let's try it to at least get
> - * access to memory reserved if the current task is killed (see
> - * out_of_memory). Once filesystems are ready to handle allocation
> - * failures more gracefully we should just bail out here.
> - */
> + /* Coredumps can quickly deplete all memory reserves */
> + if (current->flags & PF_DUMPCORE)
> + goto out;
> + /* The OOM killer will not help higher order allocs */
> + if (order > PAGE_ALLOC_COSTLY_ORDER)
> + goto out;
> + /* The OOM killer does not needlessly kill tasks for lowmem */
> + if (ac->high_zoneidx < ZONE_NORMAL)
> + goto out;
> + if (pm_suspended_storage())
> + goto out;
> + /*
> + * XXX: GFP_NOFS allocations should rather fail than rely on
> + * other request to make a forward progress.
> + * We are in an unfortunate situation where out_of_memory cannot
> + * do much for this context but let's try it to at least get
> + * access to memory reserved if the current task is killed (see
> + * out_of_memory). Once filesystems are ready to handle allocation
> + * failures more gracefully we should just bail out here.
> + */
> +
> + /* The OOM killer may not free memory on a specific node */
> + if (gfp_mask & __GFP_THISNODE)
> + goto out;
>
> - /* The OOM killer may not free memory on a specific node */
> - if (gfp_mask & __GFP_THISNODE)
> - goto out;
> - }
> /* Exhausted what can be done so it's blamo time */
> if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
> *did_some_progress = 1;
Forgot to include this part of course
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index ec9f11d4f094..12a6fce85f61 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1013,7 +1013,7 @@ bool out_of_memory(struct oom_control *oc)
* make sure exclude 0 mask - all other users should have at least
* ___GFP_DIRECT_RECLAIM to get here.
*/
- if (oc->gfp_mask && !(oc->gfp_mask & (__GFP_FS|__GFP_NOFAIL)))
+ if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS))
return true;
/*
Anyway I will think about this some more and prepapre patches with the
full changelog for further discussion.
--
Michal Hocko
SUSE Labs
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