From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752876AbcFJIoE (ORCPT ); Fri, 10 Jun 2016 04:44:04 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:36083 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751700AbcFJInz (ORCPT ); Fri, 10 Jun 2016 04:43:55 -0400 From: Michal Hocko To: Andrew Morton Cc: Cristopher Lameter , David Rientjes , Joonsoo Kim , Pekka Enberg , , LKML , Michal Hocko Subject: [PATCH 2/2] slab: do not panic on invalid gfp_mask Date: Fri, 10 Jun 2016 10:43:20 +0200 Message-Id: <1465548200-11384-2-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1465548200-11384-1-git-send-email-mhocko@kernel.org> References: <1465548200-11384-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko both SLAB and SLUB BUG() when a caller provides an invalid gfp_mask. This is a rather harsh way to announce a non-critical issue. Allocator is free to ignore invalid flags. Let's simply replace BUG() by dump_stack to tell the offender and fixup the mask to move on with the allocation request. This is an example for kmalloc(GFP_KERNEL|__GFP_HIGHMEM) from a test module. [ 31.914753] Unexpected gfp: 0x2 (__GFP_HIGHMEM). Fixing up to gfp: 0x24000c0 (GFP_KERNEL). Fix your code! [ 31.914754] CPU: 0 PID: 2916 Comm: insmod Tainted: G O 4.6.0-slabgfp2-00002-g4cdfc2ef4892-dirty #936 [ 31.914755] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 31.914756] 0000000000000000 ffff88000d777c00 ffffffff8130e2fb ffff88000ec006c0 [ 31.914758] 000000000000000c ffff88000d777c58 ffffffff811791dd 0000000000000246 [ 31.914759] 0000000000000246 0000000000000046 00000002024000c0 ffff88000fa1d888 [ 31.914759] Call Trace: [ 31.914760] [] dump_stack+0x67/0x90 [ 31.914762] [] cache_alloc_refill+0x201/0x617 [ 31.914763] [] kmem_cache_alloc_trace+0xa7/0x24a [ 31.914764] [] ? 0xffffffffa0005000 [ 31.914765] [] mymodule_init+0x20/0x1000 [test_slab] [ 31.914767] [] do_one_initcall+0xe7/0x16c [ 31.914768] [] ? rcu_read_lock_sched_held+0x61/0x69 [ 31.914769] [] ? kmem_cache_alloc_trace+0x197/0x24a [ 31.914771] [] do_init_module+0x5f/0x1d9 [ 31.914772] [] load_module+0x1a3d/0x1f21 [ 31.914774] [] ? retint_kernel+0x2d/0x2d [ 31.914775] [] SyS_init_module+0xe8/0x10e [ 31.914776] [] ? SyS_init_module+0xe8/0x10e [ 31.914778] [] do_syscall_64+0x68/0x13f [ 31.914779] [] entry_SYSCALL64_slow_path+0x25/0x25 Signed-off-by: Michal Hocko --- mm/slab.c | 6 ++++-- mm/slub.c | 5 +++-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 03fb724d6e48..fc9496bdd038 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2687,8 +2687,10 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, */ if (unlikely(flags & GFP_SLAB_BUG_MASK)) { gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; - pr_emerg("Unexpected gfp: %#x (%pGg)\n", invalid_mask, &invalid_mask); - BUG(); + flags &= ~GFP_SLAB_BUG_MASK; + pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", + invalid_mask, &invalid_mask, flags, &flags); + dump_stack(); } local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); diff --git a/mm/slub.c b/mm/slub.c index dd5a9eee7df5..ca60b414e569 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1629,8 +1629,9 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) { if (unlikely(flags & GFP_SLAB_BUG_MASK)) { gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; - pr_emerg("Unexpected gfp: %#x (%pGg)\n", invalid_mask, &invalid_mask); - BUG(); + flags &= ~GFP_SLAB_BUG_MASK; + pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", + invalid_mask, &invalid_mask, flags, &flags); } return allocate_slab(s, -- 2.8.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f198.google.com (mail-lb0-f198.google.com [209.85.217.198]) by kanga.kvack.org (Postfix) with ESMTP id 23EDD6B007E for ; Fri, 10 Jun 2016 04:43:55 -0400 (EDT) Received: by mail-lb0-f198.google.com with SMTP id na2so24169318lbb.1 for ; Fri, 10 Jun 2016 01:43:55 -0700 (PDT) Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com. [74.125.82.67]) by mx.google.com with ESMTPS id j201si42982035wmg.66.2016.06.10.01.43.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Jun 2016 01:43:53 -0700 (PDT) Received: by mail-wm0-f67.google.com with SMTP id r5so16229703wmr.0 for ; Fri, 10 Jun 2016 01:43:53 -0700 (PDT) From: Michal Hocko Subject: [PATCH 2/2] slab: do not panic on invalid gfp_mask Date: Fri, 10 Jun 2016 10:43:20 +0200 Message-Id: <1465548200-11384-2-git-send-email-mhocko@kernel.org> In-Reply-To: <1465548200-11384-1-git-send-email-mhocko@kernel.org> References: <1465548200-11384-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Cristopher Lameter , David Rientjes , Joonsoo Kim , Pekka Enberg , linux-mm@kvack.org, LKML , Michal Hocko From: Michal Hocko both SLAB and SLUB BUG() when a caller provides an invalid gfp_mask. This is a rather harsh way to announce a non-critical issue. Allocator is free to ignore invalid flags. Let's simply replace BUG() by dump_stack to tell the offender and fixup the mask to move on with the allocation request. This is an example for kmalloc(GFP_KERNEL|__GFP_HIGHMEM) from a test module. [ 31.914753] Unexpected gfp: 0x2 (__GFP_HIGHMEM). Fixing up to gfp: 0x24000c0 (GFP_KERNEL). Fix your code! [ 31.914754] CPU: 0 PID: 2916 Comm: insmod Tainted: G O 4.6.0-slabgfp2-00002-g4cdfc2ef4892-dirty #936 [ 31.914755] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 31.914756] 0000000000000000 ffff88000d777c00 ffffffff8130e2fb ffff88000ec006c0 [ 31.914758] 000000000000000c ffff88000d777c58 ffffffff811791dd 0000000000000246 [ 31.914759] 0000000000000246 0000000000000046 00000002024000c0 ffff88000fa1d888 [ 31.914759] Call Trace: [ 31.914760] [] dump_stack+0x67/0x90 [ 31.914762] [] cache_alloc_refill+0x201/0x617 [ 31.914763] [] kmem_cache_alloc_trace+0xa7/0x24a [ 31.914764] [] ? 0xffffffffa0005000 [ 31.914765] [] mymodule_init+0x20/0x1000 [test_slab] [ 31.914767] [] do_one_initcall+0xe7/0x16c [ 31.914768] [] ? rcu_read_lock_sched_held+0x61/0x69 [ 31.914769] [] ? kmem_cache_alloc_trace+0x197/0x24a [ 31.914771] [] do_init_module+0x5f/0x1d9 [ 31.914772] [] load_module+0x1a3d/0x1f21 [ 31.914774] [] ? retint_kernel+0x2d/0x2d [ 31.914775] [] SyS_init_module+0xe8/0x10e [ 31.914776] [] ? SyS_init_module+0xe8/0x10e [ 31.914778] [] do_syscall_64+0x68/0x13f [ 31.914779] [] entry_SYSCALL64_slow_path+0x25/0x25 Signed-off-by: Michal Hocko --- mm/slab.c | 6 ++++-- mm/slub.c | 5 +++-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 03fb724d6e48..fc9496bdd038 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2687,8 +2687,10 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, */ if (unlikely(flags & GFP_SLAB_BUG_MASK)) { gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; - pr_emerg("Unexpected gfp: %#x (%pGg)\n", invalid_mask, &invalid_mask); - BUG(); + flags &= ~GFP_SLAB_BUG_MASK; + pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", + invalid_mask, &invalid_mask, flags, &flags); + dump_stack(); } local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); diff --git a/mm/slub.c b/mm/slub.c index dd5a9eee7df5..ca60b414e569 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1629,8 +1629,9 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) { if (unlikely(flags & GFP_SLAB_BUG_MASK)) { gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; - pr_emerg("Unexpected gfp: %#x (%pGg)\n", invalid_mask, &invalid_mask); - BUG(); + flags &= ~GFP_SLAB_BUG_MASK; + pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", + invalid_mask, &invalid_mask, flags, &flags); } return allocate_slab(s, -- 2.8.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org