On Fri, Jun 09, 2017 at 01:38:09PM -0400, Brian Foster wrote:
> Log recovery allocates in-core transaction and member item data
> structures on-demand as it processes the on-disk log. Transactions
> are allocated on first encounter on-disk and stored in a hash table
> structure where they are easily accessible for subsequent lookups.
> Transaction items are also allocated on demand and are attached to
> the associated transactions.
>
> When a commit record is encountered in the log, the transaction is
> committed to the fs and the in-core structures are freed. If a
> filesystem crashes or shuts down before all in-core log buffers are
> flushed to the log, however, not all transactions may have commit
> records in the log. As expected, the modifications in such an
> incomplete transaction are not replayed to the fs. The in-core data
> structures for the partial transaction are never freed, however,
> resulting in a memory leak.
>
> Update xlog_do_recovery_pass() to walk the hash table of transaction
> lists as the last step before it goes out of scope and free any
> transactions that may remain on the lists. This prevents a memory
> leak of partial transactions in the log.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Bill O'Donnell <billodo@xxxxxxxxxx>
> ---
>
> FYI, I suspect this has been a problem for a while and and rare/harmless
> enough that this can target 4.13.
>
> Brian
>
> fs/xfs/xfs_log_recover.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 4a98762..37b34c5 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -5224,6 +5224,7 @@ xlog_do_recovery_pass(
> int error2 = 0;
> int bblks, split_bblks;
> int hblks, split_hblks, wrapped_hblks;
> + int i;
> struct hlist_head rhash[XLOG_RHASH_SIZE];
> LIST_HEAD (buffer_list);
>
> @@ -5466,6 +5467,19 @@ xlog_do_recovery_pass(
> if (error && first_bad)
> *first_bad = rhead_blk;
>
> + /*
> + * Transactions are freed at commit time but transactions without commit
> + * records on disk are never committed. Free any that may be left in the
> + * hash table.
> + */
> + for (i = 0; i < XLOG_RHASH_SIZE; i++) {
> + struct hlist_node *tmp;
> + struct xlog_recover *trans;
> +
> + hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
> + xlog_recover_free_trans(trans);
> + }
> +
> return error ? error : error2;
> }
>
> --
> 2.7.5
>
> --
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