From: Luis Chamberlain <mcgrof@kernel.org>
To: Greg KH <gregkh@linuxfoundation.org>,
David Laight <David.Laight@aculab.com>
Cc: akpm@linux-foundation.org, minchan@kernel.org, jeyu@kernel.org,
ngupta@vflare.org, sergey.senozhatsky.work@gmail.com,
rafael@kernel.org, axboe@kernel.dk, tj@kernel.org,
mbenes@suse.com, jpoimboe@redhat.com, tglx@linutronix.de,
keescook@chromium.org, jikos@kernel.org, rostedt@goodmis.org,
peterz@infradead.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 2/3] zram: fix deadlock with sysfs attribute usage and module removal
Date: Tue, 27 Jul 2021 10:35:10 -0700 [thread overview]
Message-ID: <YQBDzoSohQ0wbLN4@bombadil.infradead.org> (raw)
In-Reply-To: <20210723174919.ka3tzyre432uilf7@garbanzo>
On Fri, Jul 23, 2021 at 10:49:19AM -0700, Luis Chamberlain wrote:
> We are talking about sysfs files and you're argument is that
> try_module_get() should lock the module, and so cannot be used
> in sysfs files. My point is that such module lock is inferred:
>
> 1) Sysfs files are created by a module, that same module is responsible
> for removing the same sysfs files.
> 2) The module can only be removed and gone, once *all* sysfs files are
> removed first.
> 3) If any of the module's sysfs files are present the module must
> still be present
> 4) kernfs ensures that if a file is opened the file will not be
> removed until any pending operation completes
> 5) If a sysfs file is used to write something, that means the
> sysfs file has not yet been removed, and we know it will
> remain in existance throughout its entire operation
> 6) When a sysfs file operation is being run, the module must
> always exist
Greg,
I'm inclined to believe my original generic solution would be better
again [0]. Specially since we can drop the dev_type_get() / dev_type_put()
stuff.
Thoughts?
[0] https://lore.kernel.org/linux-block/20210401235925.GR4332@42.do-not-panic.com/
Luis
next prev parent reply other threads:[~2021-07-27 17:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-03 0:19 [PATCH v6 0/3] zram: fix few sysfs races Luis Chamberlain
2021-07-03 0:19 ` [PATCH v6 1/3] zram: fix crashes with cpu hotplug multistate Luis Chamberlain
2021-07-03 0:19 ` [PATCH v6 2/3] zram: fix deadlock with sysfs attribute usage and module removal Luis Chamberlain
2021-07-10 19:28 ` Andrew Morton
2021-07-11 5:00 ` Greg KH
2021-07-12 23:17 ` Luis Chamberlain
2021-07-21 11:29 ` Greg KH
2021-07-22 22:17 ` Luis Chamberlain
2021-07-23 11:15 ` Greg KH
2021-07-23 17:49 ` Luis Chamberlain
2021-07-27 17:35 ` Luis Chamberlain [this message]
2021-07-03 0:19 ` [PATCH v6 3/3] zram: use ATTRIBUTE_GROUPS Luis Chamberlain
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