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b=Mw81SF0gpvuSEla2pIDdPcIqG/tRaqJACbGlO7XzjPbu5jSBzmPt53qvKof7IUwc7 YV0MyFwiismAkBUJHb+9rn6WTW/6Gc77v7O8jSTcLxVETPv9P+c030iHq0Z++AAwYU za3BfqqjgB36HbZ70DyWb9Rr2Uq7aAw2nmpFVcI4= Date: Mon, 14 Apr 2025 14:47:41 -0700 From: Andrew Morton To: Andreas Gruenbacher Cc: cgroups@vger.kernel.org, Jan Kara , Tetsuo Handa , Rafael Aquini , gfs2@lists.linux.dev, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/2] writeback: Fix false warning in inode_to_wb() Message-Id: <20250414144741.56f7e4162c5faa9f3fb5c2a6@linux-foundation.org> In-Reply-To: <20250412163914.3773459-3-agruenba@redhat.com> References: <20250412163914.3773459-1-agruenba@redhat.com> <20250412163914.3773459-3-agruenba@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 859A240002 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: 9rspp4ibt6878cis9h65waskpxqpk3he X-HE-Tag: 1744667263-147294 X-HE-Meta: U2FsdGVkX19tDG2gB5U9PfeoQdJKahqnaafp0BhYmVJb7wkmmKo6mCkj35qcNoH6KdP/5T9VF8fCU0Z5dwzxhiwz9MxSa/vq57Eq9zIPNt8dpniD4//SDgd62ZzUG17Rn4lbroLBwKlN1cj+QbEEjL3t3hxHb5jBYFdMFmK7MtLo7OUA+SuvuahLlnksAlBMvRK3FNzNCqs3WReww8PD0TsHFjUCTKV6g6HMsCeLjCCqdJqyJcy0AF0LGlr2YvbfhUFPbEeHiM6wuPqoBlY5Z1HukPmsi0wix2mscpOQzk+xS+wRdXp3wDw/qcxFRKQO/arpM23qakatw+wrvCVUygDLlzdZnWd3YKY8zZezUcwjyoG4CUZgqMiS4qVFq/3DHyroSUDBFycO9OK0t82ccLQP7qZ5TZ5Wg4Ooh9UCJ9/qh8UrlhHZD/o6B257i4B5C0z506Kfhn6dCP3CuTDNqf09MNQVvPrG39escLA9i9IGLWAlMNDR4tXH438C7bOVDvRlwnPvfCXlxK/glojGcaNtYM0YwZmjvVqcClnFmnkOs0zsKQ8HdfwFy+scCIcGRQB/t3Q3Zr8IZ/Z/4PU53XHTwqw0rbfe2F3ngsImrWmpM/vfVUcbf9sQNznC3wyKxqLRrpS6DBihrexXE7NvUxXnkDUZCQNhyC1VxMW8r44n7GDzeZxfP0UuSOt1u5C8sIFri3pNNspMdYxFU5T669gdyHajj+oksw6W1+GuLS6vWpTlRT4AaBUfz2tafcIwmKVprPi9Wi/xUyzK32+GTxXxDqdrdZEWGBhPRtHqHh92HoD6c332mqI0iy/7alP/H9wEOOHsTgQyed4ABnVO1bbScGpyQbHT0kF47vCbM/aiQRlEtuz+9SE0c00f5hvb+fxpWI1cQS9ozUR6NixcfOG/I1mWIxd0GYEdRDLfnC+3YygAy+9ElDIKnZzGKh5fGj6ia7YwOkfWPmJOFv7 jbSlOb3w yiGTkrO2ACMWXKu5Az2j6lKZCjyDtPYuGAEf7izjx8aCC3KMiErvtR7jfDEwlCIScMV85cgCkZZbTGlfau2Xgq+YnBUNttUz6/asqj3M4yPsXIztyvOaTj+uokP1fyD/hbpQQgJs/dOs3httsTQ6+gmNUp3Hy/zba59gclFfTo/yrjIDbVveoFjvyNaoCceEPFvW/2mXfBLWl+UWUzQmS8Fl8cRAsrlGsYCOSru2lsPPI44NPrEei0RiFLTuTjs5NIET2xlUbnBJ3jlexeM6WeGRGM6mmt/Tlelr7gBTqEd/iSocKNvI9Szkdt0h2mIuQXv22 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 12 Apr 2025 18:39:12 +0200 Andreas Gruenbacher wrote: > From: Jan Kara > > inode_to_wb() is used also for filesystems that don't support cgroup > writeback. For these filesystems inode->i_wb is stable during the > lifetime of the inode (it points to bdi->wb) and there's no need to hold > locks protecting the inode->i_wb dereference. Improve the warning in > inode_to_wb() to not trigger for these filesystems. > > ... > > --- a/include/linux/backing-dev.h > +++ b/include/linux/backing-dev.h > @@ -249,6 +249,7 @@ static inline struct bdi_writeback *inode_to_wb(const struct inode *inode) > { > #ifdef CONFIG_LOCKDEP > WARN_ON_ONCE(debug_locks && > + (inode->i_sb->s_iflags & SB_I_CGROUPWB) && > (!lockdep_is_held(&inode->i_lock) && > !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) && > !lockdep_is_held(&inode->i_wb->list_lock))); Is this a does-nothing now GFS2 has been altered? Otherwise, a bogus WARN is something we'll want to eliminate from -stable kernels also. Are we able to identify a Fixes: for this? Thanks.