From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:51546 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732375AbfHHOkQ (ORCPT ); Thu, 8 Aug 2019 10:40:16 -0400 Subject: Re: [PATCH] direct-io: use GFP_NOIO to avoid deadlock References: From: Junxiao Bi Message-ID: Date: Thu, 8 Aug 2019 07:39:45 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Mikulas Patocka , Alexander Viro , "Darrick J. Wong" , Mike Snitzer Cc: dm-devel@redhat.com, Alasdair Kergon , honglei.wang@oracle.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Hi Mikulas, This seemed not issue on mainline, mutex in dm_bufio_shrink_count() had been removed from mainline. Thanks, Junxiao. On 8/8/19 2:50 AM, Mikulas Patocka wrote: > A deadlock with this stacktrace was observed. > > The obvious problem here is that in the call chain > xfs_vm_direct_IO->__blockdev_direct_IO->do_blockdev_direct_IO->kmem_cache_alloc > we do a GFP_KERNEL allocation while we are in a filesystem driver and in a > block device driver. > > This patch changes the direct-io code to use GFP_NOIO. > > PID: 474 TASK: ffff8813e11f4600 CPU: 10 COMMAND: "kswapd0" > #0 [ffff8813dedfb938] __schedule at ffffffff8173f405 > #1 [ffff8813dedfb990] schedule at ffffffff8173fa27 > #2 [ffff8813dedfb9b0] schedule_timeout at ffffffff81742fec > #3 [ffff8813dedfba60] io_schedule_timeout at ffffffff8173f186 > #4 [ffff8813dedfbaa0] bit_wait_io at ffffffff8174034f > #5 [ffff8813dedfbac0] __wait_on_bit at ffffffff8173fec8 > #6 [ffff8813dedfbb10] out_of_line_wait_on_bit at ffffffff8173ff81 > #7 [ffff8813dedfbb90] __make_buffer_clean at ffffffffa038736f [dm_bufio] > #8 [ffff8813dedfbbb0] __try_evict_buffer at ffffffffa0387bb8 [dm_bufio] > #9 [ffff8813dedfbbd0] dm_bufio_shrink_scan at ffffffffa0387cc3 [dm_bufio] > #10 [ffff8813dedfbc40] shrink_slab at ffffffff811a87ce > #11 [ffff8813dedfbd30] shrink_zone at ffffffff811ad778 > #12 [ffff8813dedfbdc0] kswapd at ffffffff811ae92f > #13 [ffff8813dedfbec0] kthread at ffffffff810a8428 > #14 [ffff8813dedfbf50] ret_from_fork at ffffffff81745242 > > PID: 14127 TASK: ffff881455749c00 CPU: 11 COMMAND: "loop1" > #0 [ffff88272f5af228] __schedule at ffffffff8173f405 > #1 [ffff88272f5af280] schedule at ffffffff8173fa27 > #2 [ffff88272f5af2a0] schedule_preempt_disabled at ffffffff8173fd5e > #3 [ffff88272f5af2b0] __mutex_lock_slowpath at ffffffff81741fb5 > #4 [ffff88272f5af330] mutex_lock at ffffffff81742133 > #5 [ffff88272f5af350] dm_bufio_shrink_count at ffffffffa03865f9 [dm_bufio] > #6 [ffff88272f5af380] shrink_slab at ffffffff811a86bd > #7 [ffff88272f5af470] shrink_zone at ffffffff811ad778 > #8 [ffff88272f5af500] do_try_to_free_pages at ffffffff811adb34 > #9 [ffff88272f5af590] try_to_free_pages at ffffffff811adef8 > #10 [ffff88272f5af610] __alloc_pages_nodemask at ffffffff811a09c3 > #11 [ffff88272f5af710] alloc_pages_current at ffffffff811e8b71 > #12 [ffff88272f5af760] new_slab at ffffffff811f4523 > #13 [ffff88272f5af7b0] __slab_alloc at ffffffff8173a1b5 > #14 [ffff88272f5af880] kmem_cache_alloc at ffffffff811f484b > #15 [ffff88272f5af8d0] do_blockdev_direct_IO at ffffffff812535b3 > #16 [ffff88272f5afb00] __blockdev_direct_IO at ffffffff81255dc3 > #17 [ffff88272f5afb30] xfs_vm_direct_IO at ffffffffa01fe3fc [xfs] > #18 [ffff88272f5afb90] generic_file_read_iter at ffffffff81198994 > #19 [ffff88272f5afc50] __dta_xfs_file_read_iter_2398 at ffffffffa020c970 [xfs] > #20 [ffff88272f5afcc0] lo_rw_aio at ffffffffa0377042 [loop] > #21 [ffff88272f5afd70] loop_queue_work at ffffffffa0377c3b [loop] > #22 [ffff88272f5afe60] kthread_worker_fn at ffffffff810a8a0c > #23 [ffff88272f5afec0] kthread at ffffffff810a8428 > #24 [ffff88272f5aff50] ret_from_fork at ffffffff81745242 > > Signed-off-by: Mikulas Patocka > Cc: stable@vger.kernel.org > > --- > fs/direct-io.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > Index: linux-2.6/fs/direct-io.c > =================================================================== > --- linux-2.6.orig/fs/direct-io.c 2019-08-02 08:51:56.000000000 +0200 > +++ linux-2.6/fs/direct-io.c 2019-08-08 11:22:18.000000000 +0200 > @@ -436,7 +436,7 @@ dio_bio_alloc(struct dio *dio, struct di > * bio_alloc() is guaranteed to return a bio when allowed to sleep and > * we request a valid number of vectors. > */ > - bio = bio_alloc(GFP_KERNEL, nr_vecs); > + bio = bio_alloc(GFP_NOIO, nr_vecs); > > bio_set_dev(bio, bdev); > bio->bi_iter.bi_sector = first_sector; > @@ -1197,7 +1197,7 @@ do_blockdev_direct_IO(struct kiocb *iocb > if (iov_iter_rw(iter) == READ && !count) > return 0; > > - dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); > + dio = kmem_cache_alloc(dio_cache, GFP_NOIO); > retval = -ENOMEM; > if (!dio) > goto out;