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Commit ba443916 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Tso
Browse files

ext4: Fix lockdep warning 

We should not call ext4_mb_add_n_trim while holding alloc_semp.

    =============================================
    [ INFO: possible recursive locking detected ]
    2.6.29-rc4-git1-dirty #124
    ---------------------------------------------
    ffsb/3116 is trying to acquire lock:
     (&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
     ext4_mb_load_buddy+0xd2/0x343

    but task is already holding lock:
     (&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
     ext4_mb_load_buddy+0xd2/0x343

http://bugzilla.kernel.org/show_bug.cgi?id=12672



Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 7be2baaa

fs/ext4/mballoc.c

+16 −13
Original line number Diff line number Diff line
@@ -4476,23 +4476,26 @@ static int ext4_mb_release_context(struct ext4_allocation_context *ac) 
			pa->pa_free -= ac->ac_b_ex.fe_len;

			pa->pa_len -= ac->ac_b_ex.fe_len;

			spin_unlock(&pa->pa_lock);

		}

	}

	if (ac->alloc_semp)

		up_read(ac->alloc_semp);

	if (pa) {

		/*

		 * We want to add the pa to the right bucket.

		 * Remove it from the list and while adding

		 * make sure the list to which we are adding

			 * doesn't grow big.

		 * doesn't grow big.  We need to release

		 * alloc_semp before calling ext4_mb_add_n_trim()

		 */

			if (likely(pa->pa_free)) {

		if (pa->pa_linear && likely(pa->pa_free)) {

			spin_lock(pa->pa_obj_lock);

			list_del_rcu(&pa->pa_inode_list);

			spin_unlock(pa->pa_obj_lock);

			ext4_mb_add_n_trim(ac);

		}

		}

		ext4_mb_put_pa(ac, ac->ac_sb, pa);

	}

	if (ac->alloc_semp)

		up_read(ac->alloc_semp);

	if (ac->ac_bitmap_page)

		page_cache_release(ac->ac_bitmap_page);

	if (ac->ac_buddy_page)