From: Matthew Wilcox <willy@infradead.org>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-kernel@vger.kernel.org,
"Toralf Förster" <toralf.foerster@gmx.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Jens Axboe" <axboe@kernel.dk>,
linux-mm@kvack.org
Subject: Re: [PATCH -mm] mm: readahead: apply a default readahead size
Date: Tue, 29 Dec 2020 22:23:11 +0000 [thread overview]
Message-ID: <20201229222311.GD28221@casper.infradead.org> (raw)
In-Reply-To: <20201229212634.31307-1-rdunlap@infradead.org>
On Tue, Dec 29, 2020 at 01:26:34PM -0800, Randy Dunlap wrote:
> UBSAN reports an invalid shift size:
>
> mr-fox kernel: UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
> mr-fox kernel: shift exponent 64 is too large for 64-bit type 'long unsigned int'
>
> Original report:
> https://lore.kernel.org/lkml/c6e5eb81-680f-dd5c-8a81-62041a5ce50c@gmx.de/
>
> Follow-up report:
> https://lore.kernel.org/lkml/0c283ea9-b446-0e40-6dc8-e9585ae171b4@gmx.de/T/#m9b604660925f9e8a544f7453130c31d083c1e5bb
>
>
> Willy suggested that get_init_ra_size() was being called with a size of 0,
> which would cause this (instead of some Huge value), so add a check in
> that function for size == 0, and if 0, default it to 32 (pages).
No, this is wrong. 'size' in this case is the size of the read.
And it's zero. Is this fixed by commit
3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3
next prev parent reply other threads:[~2020-12-29 22:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 21:26 [PATCH -mm] mm: readahead: apply a default readahead size Randy Dunlap
2020-12-29 22:23 ` Matthew Wilcox [this message]
2020-12-29 22:55 ` Randy Dunlap
2020-12-30 9:05 ` Toralf Förster
2021-01-03 21:40 ` Toralf Förster
2021-01-03 22:32 ` Randy Dunlap
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201229222311.GD28221@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=rdunlap@infradead.org \
--cc=toralf.foerster@gmx.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).