[RFC -v2 6/8] ext3: Do not abort journal prematurely

From: Michal Hocko
Date: Tue Aug 18 2015 - 06:39:45 EST


From: Michal Hocko <mhocko@xxxxxxxx>

journal_get_undo_access is relying on GFP_NOFS allocation yet it is
essential for the journal transaction:

[ 83.256914] journal_get_undo_access: No memory for committed data
[ 83.258022] EXT3-fs: ext3_free_blocks_sb: aborting transaction: Out
of memory in __ext3_journal_get_undo_access
[ 83.259785] EXT3-fs (hdb1): error in ext3_free_blocks_sb: Out of
memory
[ 83.267130] Aborting journal on device hdb1.
[ 83.292308] EXT3-fs (hdb1): error: ext3_journal_start_sb: Detected
aborted journal
[ 83.293630] EXT3-fs (hdb1): error: remounting filesystem read-only

Since "mm: page_alloc: do not lock up GFP_NOFS allocations upon OOM"
these allocation requests are allowed to fail so we need to use
__GFP_NOFAIL to imitate the previous behavior.

Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
fs/jbd/transaction.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
index bf7474deda2f..2151b80276c3 100644
--- a/fs/jbd/transaction.c
+++ b/fs/jbd/transaction.c
@@ -886,15 +886,8 @@ int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
goto out;

repeat:
- if (!jh->b_committed_data) {
- committed_data = jbd_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 = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS | __GFP_NOFAIL);

jbd_lock_bh_state(bh);
if (!jh->b_committed_data) {
--
2.5.0

--
Michal Hocko
SUSE Labs
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