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    Subject[PATCH AUTOSEL for 4.9 32/33] md: free unused memory after bitmap resize
    Date
    From: Zdenek Kabelac <zkabelac@redhat.com>

    [ Upstream commit 0868b99c214a3d55486c700de7c3f770b7243e7c ]

    When bitmap is resized, the old kalloced chunks just are not released
    once the resized bitmap starts to use new space.

    This fixes in particular kmemleak reports like this one:

    unreferenced object 0xffff8f4311e9c000 (size 4096):
    comm "lvm", pid 19333, jiffies 4295263268 (age 528.265s)
    hex dump (first 32 bytes):
    02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80 ................
    02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80 ................
    backtrace:
    [<ffffffffa69471ca>] kmemleak_alloc+0x4a/0xa0
    [<ffffffffa628c10e>] kmem_cache_alloc_trace+0x14e/0x2e0
    [<ffffffffa676cfec>] bitmap_checkpage+0x7c/0x110
    [<ffffffffa676d0c5>] bitmap_get_counter+0x45/0xd0
    [<ffffffffa676d6b3>] bitmap_set_memory_bits+0x43/0xe0
    [<ffffffffa676e41c>] bitmap_init_from_disk+0x23c/0x530
    [<ffffffffa676f1ae>] bitmap_load+0xbe/0x160
    [<ffffffffc04c47d3>] raid_preresume+0x203/0x2f0 [dm_raid]
    [<ffffffffa677762f>] dm_table_resume_targets+0x4f/0xe0
    [<ffffffffa6774b52>] dm_resume+0x122/0x140
    [<ffffffffa6779b9f>] dev_suspend+0x18f/0x290
    [<ffffffffa677a3a7>] ctl_ioctl+0x287/0x560
    [<ffffffffa677a693>] dm_ctl_ioctl+0x13/0x20
    [<ffffffffa62d6b46>] do_vfs_ioctl+0xa6/0x750
    [<ffffffffa62d7269>] SyS_ioctl+0x79/0x90
    [<ffffffffa6956d41>] entry_SYSCALL_64_fastpath+0x1f/0xc2

    Signed-off-by: Zdenek Kabelac <zkabelac@redhat.com>
    Signed-off-by: Shaohua Li <shli@fb.com>
    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    ---
    drivers/md/bitmap.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
    index fb02c3979bf4..f7ff408567ad 100644
    --- a/drivers/md/bitmap.c
    +++ b/drivers/md/bitmap.c
    @@ -2084,6 +2084,7 @@ int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
    for (k = 0; k < page; k++) {
    kfree(new_bp[k].map);
    }
    + kfree(new_bp);

    /* restore some fields from old_counts */
    bitmap->counts.bp = old_counts.bp;
    @@ -2134,6 +2135,14 @@ int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
    block += old_blocks;
    }

    + if (bitmap->counts.bp != old_counts.bp) {
    + unsigned long k;
    + for (k = 0; k < old_counts.pages; k++)
    + if (!old_counts.bp[k].hijacked)
    + kfree(old_counts.bp[k].map);
    + kfree(old_counts.bp);
    + }
    +
    if (!init) {
    int i;
    while (block < (chunks << chunkshift)) {
    --
    2.11.0
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