From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>, Nick Piggin <npiggin@gmail.com>,
linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org,
Eric Dumazet <edumazet@google.com>
Subject: skb_splice_bits() and large chunks in pipe (was Re: xfs_file_splice_read: possible circular locking dependency detected
Date: Sun, 18 Sep 2016 20:31:12 +0100 [thread overview]
Message-ID: <20160918193112.GF2356@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20160917190023.GA8039@ZenIV.linux.org.uk>
FWIW, I'm not sure if skb_splice_bits() can't land us in trouble; fragments
might come from compound pages and I'm not entirely convinced that we won't
end up with coalesced fragments putting more than PAGE_SIZE into a single
pipe_buffer. And that could badly confuse a bunch of code.
Can that legitimately happen? If so, we'll need to audit quite a few
->splice_write()-related codepaths; FUSE, in particular, is very likely
to be unhappy with that kind of stuff, and it's not the only place where
we might count upon never seeing e.g. longer than PAGE_SIZE chunks in
bio_vec. It shouldn't be all that hard to fix, but if the whole thing
is simply impossible, I would rather avoid that round of RTFS at the moment...
Comments?
next parent reply other threads:[~2016-09-18 19:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+55aFxrqCng2Qxasc9pyMrKUGFjo==fEaFT1vkH9Lncte3RgQ@mail.gmail.com>
[not found] ` <20160909023452.GO2356@ZenIV.linux.org.uk>
[not found] ` <CA+55aFwHQMjO4-vtfB9-ytc=o+DRo-HXVGckvXLboUxgpwb7_g@mail.gmail.com>
[not found] ` <20160909221945.GQ2356@ZenIV.linux.org.uk>
[not found] ` <CA+55aFzTOOB6oEVaaGD0N7Uznk-W9+ULPwzsxS_L_oZqGVSeLA@mail.gmail.com>
[not found] ` <20160914031648.GB2356@ZenIV.linux.org.uk>
[not found] ` <CA+55aFznQaOWoSMNphgGJJWZ=8-odrc0DAUMzfGPQe+_N4UgNA@mail.gmail.com>
[not found] ` <20160914042559.GC2356@ZenIV.linux.org.uk>
[not found] ` <20160917082007.GA6489@ZenIV.linux.org.uk>
[not found] ` <20160917190023.GA8039@ZenIV.linux.org.uk>
2016-09-18 19:31 ` Al Viro [this message]
2016-09-18 20:12 ` skb_splice_bits() and large chunks in pipe (was Re: xfs_file_splice_read: possible circular locking dependency detected Linus Torvalds
2016-09-18 22:31 ` Al Viro
2016-09-19 0:18 ` Linus Torvalds
2016-09-19 0:22 ` Al Viro
2016-09-20 9:51 ` Herbert Xu
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