linux-kernel - Re: shmem_getpage_gfp VM_BUG

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]

Date:	Thu, 1 Nov 2012 16:48:41 -0700 (PDT)
From:	Hugh Dickins <hughd@...gle.com>
To:	Dave Jones <davej@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: shmem_getpage_gfp VM_BUG_ON triggered. [3.7rc2]

On Thu, 1 Nov 2012, Dave Jones wrote:
> On Thu, Nov 01, 2012 at 04:03:40PM -0700, Hugh Dickins wrote:
>  > 
>  > Except... earlier in the thread you explained how you hacked
>  > #define VM_BUG_ON(cond) WARN_ON(cond)
>  > to get this to come out as a warning instead of a bug,
>  > and now it looks as if "a user" has here done the same.
>  > 
>  > Which is very much a user's right, of course; but does
>  > make me wonder whether that user might actually be davej ;)
> 
> indirectly. I made the same change in the Fedora kernel a while ago
> to test a hypothesis that we weren't getting any VM_BUG_ON reports.

Fedora turns on CONFIG_DEBUG_VM?

All mm developers should thank you for the wider testing exposure;
but I'm not so sure that Fedora users should thank you for turning
it on - really it's for mm developers to wrap around !assertions or
more expensive checks (e.g. checking calls) in their development.

Or did I read a few months ago that some change had been made to
such definitions, and VM_BUG_ON(contents) are evaluated even when
the config option is off?  I do hope I'm mistaken on that.

Hugh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/