lkml.org 
[lkml]   [2013]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.11 55/66] mm/zswap: bugfix: memory leak when re-swapon
    Date
    3.11-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Weijie Yang <weijie.yang@samsung.com>

    commit aa9bca05a467c61dcea4142b2877d5392de5bdce upstream.

    zswap_tree is not freed when swapoff, and it got re-kmalloced in swapon,
    so a memory leak occurs.

    Free the memory of zswap_tree in zswap_frontswap_invalidate_area().

    Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
    Reviewed-by: Bob Liu <bob.liu@oracle.com>
    Cc: Minchan Kim <minchan@kernel.org>
    Reviewed-by: Minchan Kim <minchan@kernel.org>
    From: Weijie Yang <weijie.yang@samsung.com>
    Subject: [PATCH 3.11 55/66] mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    Consider the following scenario:
    thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page)
    thread 1: call zswap_frontswap_invalidate_page to invalidate entry x.
    finished, entry x and its zbud is not freed as its refcount != 0
    now, the swap_map[x] = 0
    thread 0: now call zswap_get_swap_cache_page
    swapcache_prepare return -ENOENT because entry x is not used any more
    zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM
    zswap_writeback_entry do nothing except put refcount
    Now, the memory of zswap_entry x and its zpage leak.

    Modify:
    - check the refcount in fail path, free memory if it is not referenced.

    - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path
    can be not only caused by nomem but also by invalidate.

    [akpm@linux-foundation.org: coding-style fixes]
    Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
    Reviewed-by: Bob Liu <bob.liu@oracle.com>
    Cc: Minchan Kim <minchan@kernel.org>
    Cc: <stable@vger.kernel.org>
    Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>

    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    ---
    mm/zswap.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/mm/zswap.c
    +++ b/mm/zswap.c
    @@ -816,6 +816,10 @@ static void zswap_frontswap_invalidate_a
    }
    tree->rbroot = RB_ROOT;
    spin_unlock(&tree->lock);
    +
    + zbud_destroy_pool(tree->pool);
    + kfree(tree);
    + zswap_trees[type] = NULL;
    }

    static struct zbud_ops zswap_zbud_ops = {



    \
     
     \ /
      Last update: 2013-11-02 00:01    [W:4.047 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site