From: Greg Thelen Subject: Re: [RFC 4/8] jbd, jbd2: Do not fail journal because of frozen_buffer allocation failure Date: Wed, 05 Aug 2015 09:49:24 -0700 Message-ID: References: <1438768284-30927-1-git-send-email-mhocko@kernel.org> <1438768284-30927-5-git-send-email-mhocko@kernel.org> Mime-Version: 1.0 Content-Type: text/plain Cc: LKML , 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 , Michal Hocko To: mhocko@kernel.org Return-path: In-reply-to: <1438768284-30927-5-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org mhocko@kernel.org wrote: > From: Michal Hocko > > Journal transaction might fail prematurely because the frozen_buffer > is allocated by GFP_NOFS request: > [ 72.440013] do_get_write_access: OOM for frozen_buffer > [ 72.440014] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access > [ 72.440015] EXT4-fs error (device sda1) in ext4_reserve_inode_write:4735: Out of memory > (...snipped....) > [ 72.495559] do_get_write_access: OOM for frozen_buffer > [ 72.495560] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access > [ 72.496839] do_get_write_access: OOM for frozen_buffer > [ 72.496841] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access > [ 72.505766] Aborting journal on device sda1-8. > [ 72.505851] EXT4-fs (sda1): Remounting filesystem read-only > > This wasn't a problem until "mm: page_alloc: do not lock up GFP_NOFS > allocations upon OOM" because small GPF_NOFS allocations never failed. > This allocation seems essential for the journal and GFP_NOFS is too > restrictive to the memory allocator so let's use __GFP_NOFAIL here to > emulate the previous behavior. > > jbd code has the very same issue so let's do the same there as well. > > Signed-off-by: Michal Hocko > --- > fs/jbd/transaction.c | 11 +---------- > fs/jbd2/transaction.c | 14 +++----------- > 2 files changed, 4 insertions(+), 21 deletions(-) > > diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c > index 1695ba8334a2..bf7474deda2f 100644 > --- a/fs/jbd/transaction.c > +++ b/fs/jbd/transaction.c > @@ -673,16 +673,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, > jbd_unlock_bh_state(bh); > frozen_buffer = > jbd_alloc(jh2bh(jh)->b_size, > - GFP_NOFS); > - if (!frozen_buffer) { > - printk(KERN_ERR > - "%s: OOM for frozen_buffer\n", > - __func__); > - JBUFFER_TRACE(jh, "oom!"); > - error = -ENOMEM; > - jbd_lock_bh_state(bh); > - goto done; > - } > + GFP_NOFS|__GFP_NOFAIL); > goto repeat; > } > jh->b_frozen_data = frozen_buffer; > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c > index ff2f2e6ad311..bff071e21553 100644 > --- a/fs/jbd2/transaction.c > +++ b/fs/jbd2/transaction.c > @@ -923,16 +923,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, > jbd_unlock_bh_state(bh); > frozen_buffer = > jbd2_alloc(jh2bh(jh)->b_size, > - GFP_NOFS); > - if (!frozen_buffer) { > - printk(KERN_ERR > - "%s: OOM for frozen_buffer\n", > - __func__); > - JBUFFER_TRACE(jh, "oom!"); > - error = -ENOMEM; > - jbd_lock_bh_state(bh); > - goto done; > - } > + GFP_NOFS|__GFP_NOFAIL); > goto repeat; > } > jh->b_frozen_data = frozen_buffer; > @@ -1157,7 +1148,8 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) > > repeat: > if (!jh->b_committed_data) { > - committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS); > + committed_data = jbd2_alloc(jh2bh(jh)->b_size, > + GFP_NOFS|__GFP_NOFAIL); > if (!committed_data) { > printk(KERN_ERR "%s: No memory for committed data\n", > __func__); Is this "if (!committed_data) {" check now dead code? I also see other similar suspected dead sites in the rest of the series. -- 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