mhocko@xxxxxxxxxx wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> 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 <mhocko@xxxxxxxx>
> ---
> 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.
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