From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by kanga.kvack.org (Postfix) with ESMTP id DF61F6B02A0 for ; Tue, 13 Nov 2018 00:56:43 -0500 (EST) Received: by mail-pg1-f198.google.com with SMTP id q62so6007777pgq.9 for ; Mon, 12 Nov 2018 21:56:43 -0800 (PST) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id k13si13373990pgb.343.2018.11.12.21.52.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Nov 2018 21:52:42 -0800 (PST) From: Sasha Levin Subject: [PATCH AUTOSEL 4.9 17/17] mm: don't warn about large allocations for slab Date: Tue, 13 Nov 2018 00:52:23 -0500 Message-Id: <20181113055223.79060-17-sashal@kernel.org> In-Reply-To: <20181113055223.79060-1-sashal@kernel.org> References: <20181113055223.79060-1-sashal@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm@kvack.org From: Dmitry Vyukov [ Upstream commit 61448479a9f2c954cde0cfe778cb6bec5d0a748d ] Slub does not call kmalloc_slab() for sizes > KMALLOC_MAX_CACHE_SIZE, instead it falls back to kmalloc_large(). For slab KMALLOC_MAX_CACHE_SIZE == KMALLOC_MAX_SIZE and it calls kmalloc_slab() for all allocations relying on NULL return value for over-sized allocations. This inconsistency leads to unwanted warnings from kmalloc_slab() for over-sized allocations for slab. Returning NULL for failed allocations is the expected behavior. Make slub and slab code consistent by checking size > KMALLOC_MAX_CACHE_SIZE in slab before calling kmalloc_slab(). While we are here also fix the check in kmalloc_slab(). We should check against KMALLOC_MAX_CACHE_SIZE rather than KMALLOC_MAX_SIZE. It all kinda worked because for slab the constants are the same, and slub always checks the size against KMALLOC_MAX_CACHE_SIZE before kmalloc_slab(). But if we get there with size > KMALLOC_MAX_CACHE_SIZE anyhow bad things will happen. For example, in case of a newly introduced bug in slub code. Also move the check in kmalloc_slab() from function entry to the size > 192 case. This partially compensates for the additional check in slab code and makes slub code a bit faster (at least theoretically). Also drop __GFP_NOWARN in the warning check. This warning means a bug in slab code itself, user-passed flags have nothing to do with it. Nothing of this affects slob. Link: http://lkml.kernel.org/r/20180927171502.226522-1-dvyukov@gmail.com Signed-off-by: Dmitry Vyukov Reported-by: syzbot+87829a10073277282ad1@syzkaller.appspotmail.com Reported-by: syzbot+ef4e8fc3a06e9019bb40@syzkaller.appspotmail.com Reported-by: syzbot+6e438f4036df52cbb863@syzkaller.appspotmail.com Reported-by: syzbot+8574471d8734457d98aa@syzkaller.appspotmail.com Reported-by: syzbot+af1504df0807a083dbd9@syzkaller.appspotmail.com Acked-by: Christoph Lameter Acked-by: Vlastimil Babka Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/slab.c | 4 ++++ mm/slab_common.c | 12 ++++++------ 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index c59844dbd034..263dcda6897b 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3690,6 +3690,8 @@ __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) struct kmem_cache *cachep; void *ret; + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) + return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; @@ -3725,6 +3727,8 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags, struct kmem_cache *cachep; void *ret; + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) + return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; diff --git a/mm/slab_common.c b/mm/slab_common.c index 622f6b6ae844..13f1926f8fcd 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -883,18 +883,18 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) { int index; - if (unlikely(size > KMALLOC_MAX_SIZE)) { - WARN_ON_ONCE(!(flags & __GFP_NOWARN)); - return NULL; - } - if (size <= 192) { if (!size) return ZERO_SIZE_PTR; index = size_index[size_index_elem(size)]; - } else + } else { + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { + WARN_ON(1); + return NULL; + } index = fls(size - 1); + } #ifdef CONFIG_ZONE_DMA if (unlikely((flags & GFP_DMA))) -- 2.17.1