From: Michal Hocko Subject: Re: [RFC -v2 7/8] btrfs: Prevent from early transaction abort Date: Tue, 18 Aug 2015 13:01:52 +0200 Message-ID: <20150818110151.GI5033@dhcp22.suse.cz> References: <1438768284-30927-1-git-send-email-mhocko@kernel.org> <1438768284-30927-8-git-send-email-mhocko@kernel.org> <20150818104031.GF5033@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Johannes Weiner , Tetsuo Handa , Dave Chinner , Theodore Ts'o , linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, Jan Kara To: LKML Return-path: Content-Disposition: inline In-Reply-To: <20150818104031.GF5033@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Tue 18-08-15 12:40:31, Michal Hocko wrote: [...] > @@ -4867,9 +4865,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, > return NULL; > > for (i = 0; i < num_pages; i++, index++) { > - p = find_or_create_page(mapping, index, GFP_NOFS); > - if (!p) > - goto free_eb; > + p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL); > > spin_lock(&mapping->private_lock); > if (PagePrivate(p)) { Same here. find_or_create_page might return NULL. --- >From f430e5f54367b8815e1099f26fedd2873b597a07 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Wed, 15 Jul 2015 19:27:06 +0200 Subject: [PATCH] btrfs: Prevent from early transaction abort Btrfs relies on GFP_NOFS allocation when commiting the transaction but since "mm: page_alloc: do not lock up GFP_NOFS allocations upon OOM" those allocations are allowed to fail which can lead to a pre-mature transaction abort: [ 55.328093] Call Trace: [ 55.328890] [] dump_stack+0x4f/0x7b [ 55.330518] [] ? console_unlock+0x334/0x363 [ 55.332738] [] __alloc_pages_nodemask+0x81d/0x8d4 [ 55.334910] [] pagecache_get_page+0x10e/0x20c [ 55.336844] [] alloc_extent_buffer+0xd0/0x350 [btrfs] [ 55.338973] [] btrfs_find_create_tree_block+0x15/0x17 [btrfs] [ 55.341329] [] btrfs_alloc_tree_block+0x18c/0x405 [btrfs] [ 55.343566] [] split_leaf+0x1e4/0x6a6 [btrfs] [ 55.345577] [] btrfs_search_slot+0x671/0x831 [btrfs] [ 55.347679] [] ? get_parent_ip+0xe/0x3e [ 55.349434] [] btrfs_insert_empty_items+0x5d/0xa8 [btrfs] [ 55.351681] [] __btrfs_run_delayed_refs+0x7a6/0xf35 [btrfs] [ 55.353979] [] btrfs_run_delayed_refs+0x6e/0x226 [btrfs] [ 55.356212] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.358378] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.360626] [] btrfs_commit_transaction+0x4c/0xaba [btrfs] [ 55.362894] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.365221] [] btrfs_sync_file+0x29c/0x310 [btrfs] [ 55.367273] [] vfs_fsync_range+0x8f/0x9e [ 55.369047] [] vfs_fsync+0x1c/0x1e [ 55.370654] [] do_fsync+0x34/0x4e [ 55.372246] [] SyS_fsync+0x10/0x14 [ 55.373851] [] system_call_fastpath+0x12/0x6f [ 55.381070] BTRFS: error (device hdb1) in btrfs_run_delayed_refs:2821: errno=-12 Out of memory [ 55.382431] BTRFS warning (device hdb1): Skipping commit of aborted transaction. [ 55.382433] BTRFS warning (device hdb1): cleanup_transaction:1692: Aborting unused transaction(IO failure). [ 55.384280] ------------[ cut here ]------------ [ 55.384312] WARNING: CPU: 0 PID: 3010 at fs/btrfs/delayed-ref.c:438 btrfs_select_ref_head+0xd9/0xfe [btrfs]() [...] [ 55.384337] Call Trace: [ 55.384353] [] dump_stack+0x4f/0x7b [ 55.384357] [] ? down_trylock+0x2d/0x37 [ 55.384359] [] warn_slowpath_common+0xa1/0xbb [ 55.384398] [] ? btrfs_select_ref_head+0xd9/0xfe [btrfs] [ 55.384400] [] warn_slowpath_null+0x1a/0x1c [ 55.384423] [] btrfs_select_ref_head+0xd9/0xfe [btrfs] [ 55.384446] [] ? __btrfs_run_delayed_refs+0xa2/0xf35 [btrfs] [ 55.384455] [] __btrfs_run_delayed_refs+0xab/0xf35 [btrfs] [ 55.384476] [] btrfs_run_delayed_refs+0x6e/0x226 [btrfs] [ 55.384499] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.384521] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.384543] [] btrfs_commit_transaction+0x4c/0xaba [btrfs] [ 55.384565] [] ? start_transaction+0x192/0x534 [btrfs] [ 55.384588] [] btrfs_sync_file+0x29c/0x310 [btrfs] [ 55.384591] [] vfs_fsync_range+0x8f/0x9e [ 55.384592] [] vfs_fsync+0x1c/0x1e [ 55.384593] [] do_fsync+0x34/0x4e [ 55.384594] [] SyS_fsync+0x10/0x14 [ 55.384595] [] system_call_fastpath+0x12/0x6f [...] [ 55.384608] ---[ end trace c29799da1d4dd621 ]--- [ 55.437323] BTRFS info (device hdb1): forced readonly [ 55.438815] BTRFS info (device hdb1): delayed_refs has NO entry Fix this by reintroducing the no-fail behavior of this allocation path with the explicit __GFP_NOFAIL. Signed-off-by: Michal Hocko --- fs/btrfs/extent_io.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c374e1e71e5f..f4d6eea975d7 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4607,9 +4607,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, { struct extent_buffer *eb = NULL; - eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS); - if (eb == NULL) - return NULL; + eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL); eb->start = start; eb->len = len; eb->fs_info = fs_info; @@ -4867,7 +4865,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, return NULL; for (i = 0; i < num_pages; i++, index++) { - p = find_or_create_page(mapping, index, GFP_NOFS); + p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL); if (!p) goto free_eb; -- 2.5.0 -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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