linux-kernel - Re: [syzbot] [mm?] BUG: Bad page map (7)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZP9mla26MWqKKUZ7@casper.infradead.org>
Date:   Mon, 11 Sep 2023 20:12:21 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Yin Fengwei <fengwei.yin@...el.com>,
        syzbot <syzbot+55cc72f8cc3a549119df@...kaller.appspotmail.com>,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] BUG: Bad page map (7)

On Mon, Sep 11, 2023 at 09:55:37AM -0700, Dave Hansen wrote:
> On 9/11/23 09:44, Matthew Wilcox wrote:
> > After fixing your two typos, this assembles to 176 bytes more code than
> > my version.  Not sure that's great.
> 
> Maybe I'm a fool, but 176 bytes of text bloat isn't scaring me off too
> much.  I'd much rather have that than another window into x86 goofiness
> to maintain.
> 
> Does that 176 bytes translate into meaningful performance, or is it just
> a bunch of register bit twiddling that the CPU will sail through?

I'm ... not sure how to tell.  It's 1120 bytes vs 944 bytes and crawling
through that much x86 assembly isn't my idea of a great time.  I can
send you objdump -dr for all three options if you like?  Maybe there's
a quick way to compare them that I've never known about.