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    SubjectRe: [linux-pm] 2 bugs related to suspend to disk
    hi,

    On Sun, 24 May 2009, Rafael J. Wysocki wrote:

    > On Sunday 24 May 2009, Marcin Slusarz wrote:
    > > 1) echo platform > /sys/power/disk; echo disk > /sys/power/state
    > >
    > > works but prints:
    > >
    > > BUG: sleeping function called from invalid context at include/linux/writeback.h:87
    > > in_atomic(): 1, irqs_disabled(): 0, pid: 6509, name: sh
    > > 3 locks held by sh/6509:
    > > #0: (&buffer->mutex){+.+.+.}, at: [<>] sysfs_write_file+0x38/0x119
    > > #1: (pm_mutex){+.+.+.}, at: [<>] hibernate+0x17/0x169
    > > #2: (swap_lock){+.+...}, at: [<>] swap_type_of+0x2e/0xed
    > > Pid: 6509, comm: sh Not tainted 2.6.30-rc7-mod #124
    > > Call Trace:
    > > ? __debug_show_held_locks
    > > ? bdev_test
    > > __might_sleep
    > > ifind
    > > ? bdev_test
    > > iget5_locked
    > > ? bdev_set
    > > bdget
    > > swap_type_of
    > > swsusp_write
    > > ? acpi_sleep_tts_switch
    > > hibernate
    > > state_store
    > > kobj_attr_store
    > > sysfs_write_file
    > > vfs_write
    > > sys_write
    > > system_call_fastpath
    > >
    > > 2) "s2disk" (from suspend-0.8) suspends, but doesn't resume (and I need to mkswap && swapon -a later)
    > >
    > > It's not a regression, because I never tried to STD (STR worked).
    >
    > Both look strange, at least the first one does.
    >
    > Thanks for the report, I'll do my best to take care of this as soon as I can.
    >

    i've seen a similar warning, the problem seems to be that swap_type_of
    calls bdget with the swap_lock held.

    with the attached patch i don't see this warning any more - but i'm not
    sure if this is the correct way to fix this

    regards, sebastian
    ---

    don't call bdget with swap_lock held

    Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
    ---
    mm/swapfile.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    Index: linux-2.5/mm/swapfile.c
    ===================================================================
    --- linux-2.5.orig/mm/swapfile.c 2009-03-24 13:51:00.000000000 +0100
    +++ linux-2.5/mm/swapfile.c 2009-05-25 15:33:34.000000000 +0200
    @@ -634,10 +634,10 @@ int swap_type_of(dev_t device, sector_t
    continue;

    if (!bdev) {
    + spin_unlock(&swap_lock);
    if (bdev_p)
    *bdev_p = bdget(sis->bdev->bd_dev);

    - spin_unlock(&swap_lock);
    return i;
    }
    if (bdev == sis->bdev) {
    @@ -646,10 +646,10 @@ int swap_type_of(dev_t device, sector_t
    se = list_entry(sis->extent_list.next,
    struct swap_extent, list);
    if (se->start_block == offset) {
    + spin_unlock(&swap_lock);
    if (bdev_p)
    *bdev_p = bdget(sis->bdev->bd_dev);

    - spin_unlock(&swap_lock);
    bdput(bdev);
    return i;
    }

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