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| author | Mikulas Patocka <mpatocka@redhat.com> | 2020-07-08 12:25:20 -0400 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2020-07-08 12:50:51 -0400 |
| commit | 6958c1c640af8c3f40fa8a2eee3b5b905d95b677 (patch) | |
| tree | 3ad740210f4672ce601d1f994b6eb8fcaa6f88ee /drivers/md/dm.c | |
| parent | 174364f6a8979655f71b04b6492657aec3762703 (diff) | |
| download | linux-6958c1c640af8c3f40fa8a2eee3b5b905d95b677.tar.bz2 | |
dm: use noio when sending kobject event
kobject_uevent may allocate memory and it may be called while there are dm
devices suspended. The allocation may recurse into a suspended device,
causing a deadlock. We must set the noio flag when sending a uevent.
The observed deadlock was reported here:
https://www.redhat.com/archives/dm-devel/2020-March/msg00025.html
Reported-by: Khazhismel Kumykov <khazhy@google.com>
Reported-by: Tahsin Erdogan <tahsin@google.com>
Reported-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4cc7e2599664..52449afd58eb 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -12,6 +12,7 @@ #include <linux/init.h> #include <linux/module.h> #include <linux/mutex.h> +#include <linux/sched/mm.h> #include <linux/sched/signal.h> #include <linux/blkpg.h> #include <linux/bio.h> @@ -2939,17 +2940,25 @@ EXPORT_SYMBOL_GPL(dm_internal_resume_fast); int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, unsigned cookie) { + int r; + unsigned noio_flag; char udev_cookie[DM_COOKIE_LENGTH]; char *envp[] = { udev_cookie, NULL }; + noio_flag = memalloc_noio_save(); + if (!cookie) - return kobject_uevent(&disk_to_dev(md->disk)->kobj, action); + r = kobject_uevent(&disk_to_dev(md->disk)->kobj, action); else { snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", DM_COOKIE_ENV_VAR_NAME, cookie); - return kobject_uevent_env(&disk_to_dev(md->disk)->kobj, - action, envp); + r = kobject_uevent_env(&disk_to_dev(md->disk)->kobj, + action, envp); } + + memalloc_noio_restore(noio_flag); + + return r; } uint32_t dm_next_uevent_seq(struct mapped_device *md) |