From: Linus Torvalds <torvalds@linux-foundation.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function
Date: Tue, 30 Jan 2024 19:39:55 -0800 [thread overview]
Message-ID: <CAHk-=wjyki7XCnUjaBZSobLaNqWSjg39JhaUjrMH67sYxZLmdQ@mail.gmail.com> (raw)
In-Reply-To: <20240131024626.GQ2087318@ZenIV>
On Tue, 30 Jan 2024 at 18:46, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> What's to stop ->d_revalidate() from being called in parallel with
> __dentry_kill()?
Oh, you're right.
For some reason I thought we did the d_release() _after_ the RCU grace
period, but we don't.
Why don't we, btw? It would be so much better if we did the
d_release() from __d_free(). We have all that smarts in fs/dcache.c to
decide if we need to RCU-delay it or not, and then we don't let
filesystems use it.
I assume the reason is that some 'd_delete' cases might want to sleep
etc. Still, for things like this that just want to release memory, it
would be *much* better to have d_release called when the dentry is
actually released.
Hmm. Not very many d_delete cases, but I did see a couple that
definitely want process context (dma_buf_release goes to things that
do vfree() etc).
So I guess the "make low-level filesystems do their own kfree_rcu() is
what we're doing.
In this case it's as simple as doing that
- kfree(ei);
+ kfree_rcu(ei, rcu);
and we'd just make the rcu entry a union with something that isn't
that 'is_freed' field so that it doesn't take more space.
Linus
next prev parent reply other threads:[~2024-01-31 3:40 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 19:03 [PATCH 1/6] tracefs: avoid using the ei->dentry pointer unnecessarily Linus Torvalds
2024-01-30 19:03 ` [PATCH 2/6] eventfsfs: initialize the tracefs inode properly Linus Torvalds
2024-01-30 19:48 ` Steven Rostedt
2024-01-30 19:56 ` Steven Rostedt
2024-01-30 19:49 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 3/6] tracefs: dentry lookup crapectomy Linus Torvalds
2024-01-30 23:26 ` Al Viro
2024-01-30 23:55 ` Steven Rostedt
2024-01-31 0:07 ` Al Viro
2024-01-31 0:23 ` Al Viro
2024-01-31 0:39 ` Linus Torvalds
2024-01-30 19:03 ` [PATCH 4/6] eventfs: remove unused 'd_parent' pointer field Linus Torvalds
2024-01-30 19:03 ` [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts Linus Torvalds
2024-01-30 20:55 ` Steven Rostedt
2024-01-30 21:52 ` Linus Torvalds
2024-01-30 22:56 ` Steven Rostedt
2024-01-30 22:58 ` Linus Torvalds
2024-01-30 23:04 ` Steven Rostedt
2024-01-30 22:56 ` Linus Torvalds
2024-01-30 23:06 ` Linus Torvalds
2024-01-30 23:10 ` Steven Rostedt
2024-01-30 23:25 ` Linus Torvalds
2024-01-31 0:48 ` Al Viro
2024-01-31 5:09 ` Steven Rostedt
2024-01-31 5:25 ` Linus Torvalds
2024-01-31 5:33 ` Steven Rostedt
2024-01-31 5:57 ` Linus Torvalds
2024-01-31 6:20 ` Linus Torvalds
2024-01-31 12:57 ` Steven Rostedt
2024-01-31 13:14 ` Steven Rostedt
2024-01-31 18:08 ` Linus Torvalds
2024-01-31 18:39 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function Linus Torvalds
2024-01-30 21:25 ` Steven Rostedt
2024-01-30 21:36 ` Linus Torvalds
2024-01-31 1:12 ` Al Viro
2024-01-31 2:37 ` Linus Torvalds
2024-01-31 2:46 ` Al Viro
2024-01-31 3:39 ` Linus Torvalds [this message]
2024-01-31 4:28 ` Al Viro
2024-01-31 18:00 ` Steven Rostedt
2024-01-31 23:07 ` Masami Hiramatsu
2024-01-31 23:23 ` Steven Rostedt
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