The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 38d11da522aacaa05898c734a1cec86f1e611129 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023050716-eggnog-acutely-8d74@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
38d11da522aa ("dm: don't lock fs when the map is NULL in process of resume") 7533afa1d27b ("dm: send just one event on resize, not two") 84010e519f95 ("dm ima: measure data on device remove") 8eb6fab402e2 ("dm ima: measure data on device resume") 91ccbbac1747 ("dm ima: measure data on table load") 89f871af1b26 ("dm: delay registering the gendisk") ba30585936b0 ("dm: move setting md->type into dm_setup_md_queue") 74a2b6ec9380 ("dm: cleanup cleanup_mapped_device") 2cfa582be800 ("Merge tag 'for-5.14/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 38d11da522aacaa05898c734a1cec86f1e611129 Mon Sep 17 00:00:00 2001 From: Li Lingfeng lilingfeng3@huawei.com Date: Tue, 18 Apr 2023 16:38:04 +0800 Subject: [PATCH] dm: don't lock fs when the map is NULL in process of resume
Commit fa247089de99 ("dm: requeue IO if mapping table not yet available") added a detection of whether the mapping table is available in the IO submission process. If the mapping table is unavailable, it returns BLK_STS_RESOURCE and requeues the IO. This can lead to the following deadlock problem:
dm create mount ioctl(DM_DEV_CREATE_CMD) ioctl(DM_TABLE_LOAD_CMD) do_mount vfs_get_tree ext4_get_tree get_tree_bdev sget_fc alloc_super // got &s->s_umount down_write_nested(&s->s_umount, ...); ext4_fill_super ext4_load_super ext4_read_bh submit_bio // submit and wait io end ioctl(DM_DEV_SUSPEND_CMD) dev_suspend do_resume dm_suspend __dm_suspend lock_fs freeze_bdev get_active_super grab_super // wait for &s->s_umount down_write(&s->s_umount); dm_swap_table __bind // set md->map(can't get here)
IO will be continuously requeued while holding the lock since mapping table is NULL. At the same time, mapping table won't be set since the lock is not available. Like request-based DM, bio-based DM also has the same problem.
It's not proper to just abort IO if the mapping table not available. So clear DM_SKIP_LOCKFS_FLAG when the mapping table is NULL, this allows the DM table to be loaded and the IO submitted upon resume.
Fixes: fa247089de99 ("dm: requeue IO if mapping table not yet available") Cc: stable@vger.kernel.org Signed-off-by: Li Lingfeng lilingfeng3@huawei.com Signed-off-by: Mike Snitzer snitzer@kernel.org
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 7d5c9c582ed2..cc77cf3d4109 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1168,10 +1168,13 @@ static int do_resume(struct dm_ioctl *param) /* Do we need to load a new map ? */ if (new_map) { sector_t old_size, new_size; + int srcu_idx;
/* Suspend if it isn't already suspended */ - if (param->flags & DM_SKIP_LOCKFS_FLAG) + old_map = dm_get_live_table(md, &srcu_idx); + if ((param->flags & DM_SKIP_LOCKFS_FLAG) || !old_map) suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG; + dm_put_live_table(md, srcu_idx); if (param->flags & DM_NOFLUSH_FLAG) suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG; if (!dm_suspended_md(md))