• Dave Chinner's avatar
    xfs: fix efi item leak on forced shutdown · e34a314c
    Dave Chinner authored
    After test 139, kmemleak shows:
    
    unreferenced object 0xffff880078b405d8 (size 400):
      comm "xfs_io", pid 4904, jiffies 4294909383 (age 1186.728s)
      hex dump (first 32 bytes):
        60 c1 17 79 00 88 ff ff 60 c1 17 79 00 88 ff ff  `..y....`..y....
        00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
      backtrace:
        [<ffffffff81afb04d>] kmemleak_alloc+0x2d/0x60
        [<ffffffff8115c6cf>] kmem_cache_alloc+0x13f/0x2b0
        [<ffffffff814aaa97>] kmem_zone_alloc+0x77/0xf0
        [<ffffffff814aab2e>] kmem_zone_zalloc+0x1e/0x50
        [<ffffffff8147cd6b>] xfs_efi_init+0x4b/0xb0
        [<ffffffff814a4ee8>] xfs_trans_get_efi+0x58/0x90
        [<ffffffff81455fab>] xfs_bmap_finish+0x8b/0x1d0
        [<ffffffff814851b4>] xfs_itruncate_finish+0x2c4/0x5d0
        [<ffffffff814a970f>] xfs_setattr+0x8df/0xa70
        [<ffffffff814b5c7b>] xfs_vn_setattr+0x1b/0x20
        [<ffffffff8117dc00>] notify_change+0x170/0x2e0
        [<ffffffff81163bf6>] do_truncate+0x66/0xa0
        [<ffffffff81163d0b>] sys_ftruncate+0xdb/0xe0
        [<ffffffff8103a002>] system_call_fastpath+0x16/0x1b
        [<ffffffffffffffff>] 0xffffffffffffffff
    
    The cause of the leak is that the "remove" parameter of IOP_UNPIN()
    is never set when a CIL push is aborted. This means that the EFI
    item is never freed if it was in the push being cancelled. The
    problem is specific to delayed logging, but has uncovered a couple
    of problems with the handling of IOP_UNPIN(remove).
    
    Firstly, we cannot safely call xfs_trans_del_item() from IOP_UNPIN()
    in the CIL commit failure path or the iclog write failure path
    because for delayed loging we have no transaction context. Hence we
    must only call xfs_trans_del_item() if the log item being unpinned
    has an active log item descriptor.
    
    Secondly, xfs_trans_uncommit() does not handle log item descriptor
    freeing during the traversal of log items on a transaction. It can
    reference a freed log item descriptor when unpinning an EFI item.
    Hence it needs to use a safe list traversal method to allow items to
    be removed from the transaction during IOP_UNPIN().
    Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
    Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
    e34a314c
xfs_extfree_item.c 13.9 KB