linux-kernel - Re: [PATCH] fs/dcache.c: re-add cond_resched() in shrink_dcache

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Message-ID: <CA+55aFxD1xKqbobvoHQUWc5jc9n7-7KXYeSQy-CpE0SUZHi0PQ@mail.gmail.com>
Date:   Sat, 14 Apr 2018 14:47:21 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Nikolay Borisov <nborisov@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Khazhismel Kumykov <khazhy@...gle.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        David Rientjes <rientjes@...gle.com>,
        Goldwyn Rodrigues <rgoldwyn@...e.de>,
        Jeff Mahoney <jeffm@...e.com>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [PATCH] fs/dcache.c: re-add cond_resched() in shrink_dcache_parent()

On Sat, Apr 14, 2018 at 1:58 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
>
> That breaks d_invalidate(), unfortunately.  Look at the termination
> conditions in the loop there...

Ugh. I was going to say "but that doesn't even use select_collect()",
but yeah, detach_and_collect() calls it.

It would be easy enough to just change the

                if (!list_empty(&data.select.dispose))

there to

                if (!list_empty(&data.select.found))

too.

In fact, it probably *should* do that, exactly to get the whole
"cond_resched()" call in that whole call chain too. Because as-is, it
looks like it has the same issue as shrink_dcache_parent() does..

But yeah, the fact that I didn't notice that makes me a bit nervous.
But now I triple-checked, there are no other indirect callers.

            Linus