From c953885be8772f3a7e3262949830a82e6f10d8b1 Mon Sep 17 00:00:00 2001 From: Nicolas Boichat Date: Tue, 22 Oct 2019 21:37:40 +0800 Subject: [PATCH] mm/failslab.c: by default, do not fail allocations with direct reclaim only mainline inclusion from mainline-a9659476d4b3 undefined commit a9659476d4b3 category: bugfix bugzilla: 18481 CVE: NA ------------------------------------------------- When failslab was originally written, the intention of the "ignore-gfp-wait" flag default value ("N") was to fail GFP_ATOMIC allocations. Those were defined as (__GFP_HIGH), and the code would test for __GFP_WAIT (0x10u). However, since then, __GFP_WAIT was replaced by __GFP_RECLAIM (___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM), and GFP_ATOMIC is now defined as (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM). This means that when the flag is false, almost no allocation ever fails (as even GFP_ATOMIC allocations contain ___GFP_KSWAPD_RECLAIM). Restore the original intent of the code, by ignoring calls that directly reclaim only (__GFP_DIRECT_RECLAIM), and thus, failing GFP_ATOMIC calls again by default. Link: http://lkml.kernel.org/r/20190520214514.81360-1-drinkcat@chromium.org Fixes: 71baba4b92dc1fa1 ("mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM") Signed-off-by: Nicolas Boichat Reviewed-by: Akinobu Mita Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Chenwandun Reviewed-by: Kefeng Wang Signed-off-by: Yang Yingliang --- mm/failslab.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/failslab.c b/mm/failslab.c index b135ebb88b6f..215cb1ea169d 100644 --- a/mm/failslab.c +++ b/mm/failslab.c @@ -23,7 +23,8 @@ bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags) if (gfpflags & __GFP_NOFAIL) return false; - if (failslab.ignore_gfp_reclaim && (gfpflags & __GFP_RECLAIM)) + if (failslab.ignore_gfp_reclaim && + (gfpflags & __GFP_DIRECT_RECLAIM)) return false; if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB)) -- GitLab