Messages in this thread | | | From | Shakeel Butt <> | Date | Wed, 13 Oct 2021 15:26:11 -0700 | Subject | Re: [PATCH] memcg: page_alloc: skip bulk allocator for __GFP_ACCOUNT |
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On Wed, Oct 13, 2021 at 3:03 PM Roman Gushchin <guro@fb.com> wrote: > > On Wed, Oct 13, 2021 at 12:43:38PM -0700, Shakeel Butt wrote: > > The commit 5c1f4e690eec ("mm/vmalloc: switch to bulk allocator in > > __vmalloc_area_node()") switched to bulk page allocator for order 0 > > allocation backing vmalloc. However bulk page allocator does not support > > __GFP_ACCOUNT allocations and there are several users of > > kvmalloc(__GFP_ACCOUNT). > > > > For now make __GFP_ACCOUNT allocations bypass bulk page allocator. In > > future if there is workload that can be significantly improved with the > > bulk page allocator with __GFP_ACCCOUNT support, we can revisit the > > decision. > > > > Fixes: 5c1f4e690eec ("mm/vmalloc: switch to bulk allocator in __vmalloc_area_node()") > > Signed-off-by: Shakeel Butt <shakeelb@google.com> > > --- > > mm/page_alloc.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 668edb16446a..b3acad4615d3 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -5215,6 +5215,10 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, > > unsigned int alloc_flags = ALLOC_WMARK_LOW; > > int nr_populated = 0, nr_account = 0; > > > > + /* Bulk allocator does not support memcg accounting. */ > > + if (unlikely(gfp & __GFP_ACCOUNT)) > > + goto out; > > + > > Isn't it a bit too aggressive? > > How about > if (WARN_ON_ONCE(gfp & __GFP_ACCOUNT))
We actually know that kvmalloc(__GFP_ACCOUNT) users exist and can trigger bulk page allocator through vmalloc, so I don't think the warning would be any helpful.
> gfp &= ~__GFP_ACCOUNT;
Bulk allocator is best effort, so callers have adequate fallbacks. Transparently disabling accounting would be unexpected.
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