From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 4A9D16B0005 for ; Thu, 12 Apr 2018 15:13:27 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id u11-v6so4446657pls.22 for ; Thu, 12 Apr 2018 12:13:27 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id n23si2638074pgd.345.2018.04.12.12.13.25 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 12 Apr 2018 12:13:25 -0700 (PDT) Date: Thu, 12 Apr 2018 12:13:22 -0700 From: Matthew Wilcox Subject: [PATCH v3 2/2] slab: __GFP_ZERO is incompatible with a constructor Message-ID: <20180412191322.GA21205@bombadil.infradead.org> References: <20180411060320.14458-1-willy@infradead.org> <20180411060320.14458-3-willy@infradead.org> <20180411192448.GD22494@bombadil.infradead.org> <20180411235652.GA28279@bombadil.infradead.org> <20180412142718.GA20398@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180412142718.GA20398@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Christopher Lameter Cc: linux-mm@kvack.org, Matthew Wilcox , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, Jan Kara , Jeff Layton , Mel Gorman From: Matthew Wilcox __GFP_ZERO requests that the object be initialised to all-zeroes, while the purpose of a constructor is to initialise an object to a particular pattern. We cannot do both. Add a warning to catch any users who mistakenly pass a __GFP_ZERO flag when allocating a slab with a constructor. Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators") Signed-off-by: Matthew Wilcox Acked-by: Johannes Weiner Acked-by: Vlastimil Babka Acked-by: Michal Hocko --- mm/slab.c | 2 ++ mm/slob.c | 4 +++- mm/slub.c | 2 ++ 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index 58c8cecc26ab..aca63d49b270 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2661,6 +2661,7 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, invalid_mask, &invalid_mask, flags, &flags); dump_stack(); } + WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); check_irq_off(); @@ -3067,6 +3068,7 @@ static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep, static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, gfp_t flags, void *objp, unsigned long caller) { + WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); if (!objp) return objp; if (cachep->flags & SLAB_POISON) { diff --git a/mm/slob.c b/mm/slob.c index 1a46181b675c..958173fd7c24 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -556,8 +556,10 @@ static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node) flags, node); } - if (b && c->ctor) + if (b && c->ctor) { + WARN_ON_ONCE(flags & __GFP_ZERO); c->ctor(b); + } kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags); return b; diff --git a/mm/slub.c b/mm/slub.c index a28488643603..0487d316a665 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2434,6 +2434,8 @@ static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, struct kmem_cache_cpu *c = *pc; struct page *page; + WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); + freelist = get_partial(s, flags, node, c); if (freelist) -- 2.16.3