From: Winston Wen <wentao@uniontech.com>
To: Jan Kara <jack@suse.cz>, Amir Goldstein <amir73il@gmail.com>
Cc: Vivek Trivedi <t.vivek@samsung.com>,
Orion Poplawski <orion@nwra.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-fsdevel@vger.kernel.org, Winston Wen <wentao@uniontech.com>
Subject: [PATCH] fanotify: allow freeze when waiting response for permission events
Date: Tue, 5 Mar 2024 14:18:04 +0800 [thread overview]
Message-ID: <BD33543C483B89AB+20240305061804.1186796-1-wentao@uniontech.com> (raw)
This is a long-standing issue that uninterruptible sleep in fanotify
could make system hibernation fail if the usperspace server gets frozen
before the process waiting for the response (as reported e.g. [1][2]).
A few years ago, there was an attempt to switch to interruptible sleep
while waiting [3], but that would lead to EINTR returns from open(2)
and break userspace [4], so it's been changed to only killable [5].
And the core freezer logic had been rewritten [6][7] in v6.1, allowing
freezing in uninterrupted sleep, so we can solve this problem now.
[1] https://lore.kernel.org/lkml/1518774280-38090-1-git-send-email-t.vivek@samsung.com/
[2] https://lore.kernel.org/lkml/c1bb16b7-9eee-9cea-2c96-a512d8b3b9c7@nwra.com/
[3] https://lore.kernel.org/linux-fsdevel/20190213145443.26836-1-jack@suse.cz/
[4] https://lore.kernel.org/linux-fsdevel/d0031e3a-f050-0832-fa59-928a80ffd44b@nwra.com/
[5] https://lore.kernel.org/linux-fsdevel/20190221105558.GA20921@quack2.suse.cz/
[6] https://lore.kernel.org/lkml/20220822114649.055452969@infradead.org/
[7] https://lore.kernel.org/lkml/20230908-avoid-spurious-freezer-wakeups-v4-0-6155aa3dafae@quicinc.com/
Signed-off-by: Winston Wen <wentao@uniontech.com>
---
fs/notify/fanotify/fanotify.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 1e4def21811e..285beaf5bc09 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -228,8 +228,10 @@ static int fanotify_get_response(struct fsnotify_group *group,
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
- ret = wait_event_killable(group->fanotify_data.access_waitq,
- event->state == FAN_EVENT_ANSWERED);
+ ret = wait_event_state(group->fanotify_data.access_waitq,
+ event->state == FAN_EVENT_ANSWERED,
+ TASK_KILLABLE|TASK_FREEZABLE);
+
/* Signal pending? */
if (ret < 0) {
spin_lock(&group->notification_lock);
--
2.43.0
next reply other threads:[~2024-03-05 6:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 6:18 Winston Wen [this message]
2024-03-06 17:59 ` [PATCH] fanotify: allow freeze when waiting response for permission events Jan Kara
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