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Wed, 6 Mar 2024 17:59:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap2.dmz-prg2.suse.org with ESMTPSA id +g+0A/uu6GXVHQAAn2gu4w (envelope-from ); Wed, 06 Mar 2024 17:59:23 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id A7EBEA0803; Wed, 6 Mar 2024 18:59:18 +0100 (CET) Date: Wed, 6 Mar 2024 18:59:18 +0100 From: Jan Kara To: Winston Wen Cc: Jan Kara , Amir Goldstein , Vivek Trivedi , Orion Poplawski , Peter Zijlstra , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] fanotify: allow freeze when waiting response for permission events Message-ID: <20240306175918.bvipf63nfk2d3ocw@quack3> References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Level: Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=vUvbyqbU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="+d78mB/6" X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-1.01 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.cz:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[7]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; FREEMAIL_CC(0.00)[suse.cz,gmail.com,samsung.com,nwra.com,infradead.org,vger.kernel.org]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-0.00)[29.75%] X-Spam-Score: -1.01 X-Rspamd-Queue-Id: 191DA4709 X-Spam-Flag: NO On Tue 05-03-24 14:18:04, Winston Wen wrote: > 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 Thanks and I'm glad this has finally a workable solution (keeping fingers crossed ;)). I've added the patch to my tree. Honza > --- > 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 > -- Jan Kara SUSE Labs, CR