dm: use noio when sending kobject event
commit 6958c1c640
upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
parent
ede24894e8
commit
b9fe45efa6
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@ -12,6 +12,7 @@
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/blkpg.h>
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#include <linux/bio.h>
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@ -2886,17 +2887,25 @@ EXPORT_SYMBOL_GPL(dm_internal_resume_fast);
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int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
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unsigned cookie)
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{
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int r;
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unsigned noio_flag;
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char udev_cookie[DM_COOKIE_LENGTH];
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char *envp[] = { udev_cookie, NULL };
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noio_flag = memalloc_noio_save();
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if (!cookie)
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return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
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r = kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
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else {
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snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
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DM_COOKIE_ENV_VAR_NAME, cookie);
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return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
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action, envp);
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r = kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
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action, envp);
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}
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memalloc_noio_restore(noio_flag);
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return r;
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}
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uint32_t dm_next_uevent_seq(struct mapped_device *md)
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