Commit 502be2a3 authored Dec 13, 2013 by Bob Peterson Committed by Steven Whitehouse Dec 13, 2013

GFS2: Fix slab memory leak in gfs2_bufdata



This patch fixes a slab memory leak that sometimes can occur
for files with a very short lifespan. The problem occurs when
a dinode is deleted before it has gotten to the journal properly.
In the leak scenario, the bd object is pinned for journal
committment (queued to the metadata buffers queue: sd_log_le_buf)
but is subsequently unpinned and dequeued before it finds its way
to the ail or the revoke queue. In this rare circumstance, the bd
object needs to be freed from slab memory, or it is forgotten.
We have to be very careful how we do it, though, because
multiple processes can call gfs2_remove_from_journal. In order to
avoid double-frees, only the process that does the unpinning is
allowed to free the bd.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

parent 9290a9a7

fs/gfs2/meta_io.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -258,6 +258,7 @@ void gfs2_remove_from_journal(struct buffer_head bh, struct gfs2_trans tr, int
		struct address_space *mapping = bh->b_page->mapping;
		struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
		struct gfs2_bufdata *bd = bh->b_private;
		int was_pinned = 0;

		if (test_clear_buffer_pinned(bh)) {
		trace_gfs2_pin(bd, 0);
		@@ -273,12 +274,16 @@ void gfs2_remove_from_journal(struct buffer_head bh, struct gfs2_trans tr, int
		tr->tr_num_databuf_rm++;
		}
		tr->tr_touched = 1;
		was_pinned = 1;
		brelse(bh);
		}
		if (bd) {
		spin_lock(&sdp->sd_ail_lock);
		if (bd->bd_tr) {
		gfs2_trans_add_revoke(sdp, bd);
		} else if (was_pinned) {
		bh->b_private = NULL;
		kmem_cache_free(gfs2_bufdata_cachep, bd);
		}
		spin_unlock(&sdp->sd_ail_lock);
		}

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