On 03/04/2024 16:48, Vlastimil Babka wrote: > On 4/3/24 1:39 PM, Aishwarya TCV wrote: >> >> >> On 25/03/2024 08:20, Vlastimil Babka wrote: >>> The MEMCG_KMEM integration with slab currently relies on two hooks >>> during allocation. memcg_slab_pre_alloc_hook() determines the objcg and >>> charges it, and memcg_slab_post_alloc_hook() assigns the objcg pointer >>> to the allocated object(s). >>> >>> As Linus pointed out, this is unnecessarily complex. Failing to charge >>> due to memcg limits should be rare, so we can optimistically allocate >>> the object(s) and do the charging together with assigning the objcg >>> pointer in a single post_alloc hook. In the rare case the charging >>> fails, we can free the object(s) back. >>> >>> This simplifies the code (no need to pass around the objcg pointer) and >>> potentially allows to separate charging from allocation in cases where >>> it's common that the allocation would be immediately freed, and the >>> memcg handling overhead could be saved. >>> >>> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >>> Link: https://lore.kernel.org/all/CAHk-=whYOOdM7jWy5jdrAm8LxcgCMFyk2bt8fYYvZzM4U-zAQA@xxxxxxxxxxxxxx/ >>> Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx> >>> Reviewed-by: Chengming Zhou <chengming.zhou@xxxxxxxxx> >>> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> >>> --- >>> mm/slub.c | 180 +++++++++++++++++++++++++++----------------------------------- >>> 1 file changed, 77 insertions(+), 103 deletions(-) >> >> Hi Vlastimil, >> >> When running the LTP test "memcg_limit_in_bytes" against next-master >> (next-20240402) kernel with Arm64 on JUNO, oops is observed in our CI. I >> can send the full logs if required. It is observed to work fine on >> softiron-overdrive-3000. >> >> A bisect identified 11bb2d9d91627935c63ea3e6a031fd238c846e1 as the first >> bad commit. Bisected it on the tag "next-20240402" at repo >> "https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git";. >> >> This works fine on Linux version v6.9-rc2 > > Oops, sorry, can you verify that this fixes it? > Thanks. > > ----8<---- > From b0597c220624fef4f10e26079a3ff1c86f02a12b Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka <vbabka@xxxxxxx> > Date: Wed, 3 Apr 2024 17:45:15 +0200 > Subject: [PATCH] fixup! mm, slab: move memcg charging to post-alloc hook > > The call to memcg_alloc_abort_single() is wrong, it expects a pointer to > single object, not an array. > > Reported-by: Aishwarya TCV <aishwarya.tcv@xxxxxxx> > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > --- > mm/slub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index f5b151a58b7d..b32e79629ae7 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2100,7 +2100,7 @@ bool memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru, > return true; > > if (likely(size == 1)) { > - memcg_alloc_abort_single(s, p); > + memcg_alloc_abort_single(s, *p); > *p = NULL; > } else { > kmem_cache_free_bulk(s, size, p); Tested the attached patch on next-20240302. Confirming that the test is running fine. Test run log is attached below. Test run log: -------------- memcg_limit_in_bytes 8 TPASS: process 614 is killed memcg_limit_in_bytes 9 TINFO: Test limit_in_bytes will be aligned to PAGESIZE memcg_limit_in_bytes 9 TPASS: echo 4095 > memory.limit_in_bytes passed as expected memcg_limit_in_bytes 9 TPASS: input=4095, limit_in_bytes=0 memcg_limit_in_bytes 10 TPASS: echo 4097 > memory.limit_in_bytes passed as expected memcg_limit_in_bytes 10 TPASS: input=4097, limit_in_bytes=4096 memcg_limit_in_bytes 11 TPASS: echo 1 > memory.limit_in_bytes passed as expected memcg_limit_in_bytes 11 TPASS: input=1, limit_in_bytes=0 memcg_limit_in_bytes 12 TINFO: Test invalid memory.limit_in_bytes memcg_limit_in_bytes 12 TPASS: echo -1 > memory.limit_in_bytes passed as expected memcg_limit_in_bytes 13 TPASS: echo 1.0 > memory.limit_in_bytes failed as expected memcg_limit_in_bytes 14 TPASS: echo 1xx > memory.limit_in_bytes failed as expected memcg_limit_in_bytes 15 TPASS: echo xx > memory.limit_in_bytes failed as expected Summary: passed 18 failed 0 broken 0 skipped 0 warnings 0 Thanks, Aishwarya
