Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754454AbdCBPsu (ORCPT ); Thu, 2 Mar 2017 10:48:50 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:36525 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585AbdCBPqj (ORCPT ); Thu, 2 Mar 2017 10:46:39 -0500 From: Michal Hocko To: Christoph Hellwig , Brian Foster Cc: Tetsuo Handa , Xiong Zhou , linux-xfs@vger.kernel.org, , LKML , , Michal Hocko Subject: [PATCH 1/2] xfs: allow kmem_zalloc_greedy to fail Date: Thu, 2 Mar 2017 16:45:40 +0100 Message-Id: <20170302154541.16155-1-mhocko@kernel.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170302153002.GG3213@bfoster.bfoster> References: <20170302153002.GG3213@bfoster.bfoster> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2375 Lines: 65 From: Michal Hocko Even though kmem_zalloc_greedy is documented it might fail the current code doesn't really implement this properly and loops on the smallest allowed size for ever. This is a problem because vzalloc might fail permanently - we might run out of vmalloc space or since 5d17a73a2ebe ("vmalloc: back off when the current task is killed") when the current task is killed. The later one makes the failure scenario much more probable than it used to be because it makes vmalloc() failures permanent for tasks with fatal signals pending.. Fix this by bailing out if the minimum size request failed. This has been noticed by a hung generic/269 xfstest by Xiong Zhou. fsstress: vmalloc: allocation failure, allocated 12288 of 20480 bytes, mode:0x14080c2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO), nodemask=(null) fsstress cpuset=/ mems_allowed=0-1 CPU: 1 PID: 23460 Comm: fsstress Not tainted 4.10.0-master-45554b2+ #21 Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 10/05/2016 Call Trace: dump_stack+0x63/0x87 warn_alloc+0x114/0x1c0 ? alloc_pages_current+0x88/0x120 __vmalloc_node_range+0x250/0x2a0 ? kmem_zalloc_greedy+0x2b/0x40 [xfs] ? free_hot_cold_page+0x21f/0x280 vzalloc+0x54/0x60 ? kmem_zalloc_greedy+0x2b/0x40 [xfs] kmem_zalloc_greedy+0x2b/0x40 [xfs] xfs_bulkstat+0x11b/0x730 [xfs] ? xfs_bulkstat_one_int+0x340/0x340 [xfs] ? selinux_capable+0x20/0x30 ? security_capable+0x48/0x60 xfs_ioc_bulkstat+0xe4/0x190 [xfs] xfs_file_ioctl+0x9dd/0xad0 [xfs] ? do_filp_open+0xa5/0x100 do_vfs_ioctl+0xa7/0x5e0 SyS_ioctl+0x79/0x90 do_syscall_64+0x67/0x180 entry_SYSCALL64_slow_path+0x25/0x25 fsstress keeps looping inside kmem_zalloc_greedy without any way out because vmalloc keeps failing due to fatal_signal_pending. Reported-by: Xiong Zhou Analyzed-by: Tetsuo Handa Signed-off-by: Michal Hocko --- fs/xfs/kmem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c index 339c696bbc01..ee95f5c6db45 100644 --- a/fs/xfs/kmem.c +++ b/fs/xfs/kmem.c @@ -34,6 +34,8 @@ kmem_zalloc_greedy(size_t *size, size_t minsize, size_t maxsize) size_t kmsize = maxsize; while (!(ptr = vzalloc(kmsize))) { + if (kmsize == minsize) + break; if ((kmsize >>= 1) <= minsize) kmsize = minsize; } -- 2.11.0