Commit 490c1b44 authored Mar 13, 2016 by Michal Hocko Committed by Theodore Ts'o Mar 13, 2016

jbd2: do not fail journal because of frozen_buffer allocation failure



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.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent adb7ef60

fs/jbd2/transaction.c

+5 −17

Original line number	Diff line number	Diff line
		@@ -966,14 +966,8 @@ do_get_write_access(handle_t handle, struct journal_head jh,
		if (!frozen_buffer) {
		JBUFFER_TRACE(jh, "allocate memory for buffer");
		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;
		goto out;
		}
		frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
		GFP_NOFS \| __GFP_NOFAIL);
		goto repeat;
		}
		jh->b_frozen_data = frozen_buffer;
		@@ -1226,15 +1220,9 @@ int jbd2_journal_get_undo_access(handle_t handle, struct buffer_head bh)
		goto out;

		repeat:
		if (!jh->b_committed_data) {
		committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
		if (!committed_data) {
		printk(KERN_ERR "%s: No memory for committed data\n",
		__func__);
		err = -ENOMEM;
		goto out;
		}
		}
		if (!jh->b_committed_data)
		committed_data = jbd2_alloc(jh2bh(jh)->b_size,
		GFP_NOFS\|__GFP_NOFAIL);

		jbd_lock_bh_state(bh);
		if (!jh->b_committed_data) {