From: Sasha Levin <sasha.levin@oracle.com>
To: Dave Hansen <dave.hansen@intel.com>, akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
hughd@google.com, mgorman@suse.de,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH 5/5] mm: poison page struct
Date: Wed, 08 Oct 2014 10:22:59 -0400 [thread overview]
Message-ID: <543548C3.7030003@oracle.com> (raw)
In-Reply-To: <5434630C.3070006@intel.com>
On 10/07/2014 06:02 PM, Dave Hansen wrote:
> On 09/29/2014 06:47 PM, Sasha Levin wrote:
>> struct page {
>> +#ifdef CONFIG_DEBUG_VM_POISON
>> + u32 poison_start;
>> +#endif
>> /* First double word block */
>> unsigned long flags; /* Atomic flags, some possibly
>> * updated asynchronously */
>> @@ -196,6 +199,9 @@ struct page {
>> #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
>> int _last_cpupid;
>> #endif
>> +#ifdef CONFIG_DEBUG_VM_POISON
>> + u32 poison_end;
>> +#endif
>> }
>
> Does this break slub's __cmpxchg_double_slab trick? I thought it
> required page->freelist and page->counters to be doubleword-aligned.
I'll probably have to switch it to 8 bytes anyways to make it work with
kasan. This should take care of the slub optimization as well.
> It's not like we really require this optimization when we're debugging,
> but trying to use it will unnecessarily slow things down.
>
> FWIW, if you're looking to trim down the number of lines of code, you
> could certainly play some macro tricks and #ifdef tricks.
>
> struct vm_poison {
> #ifdef CONFIG_DEBUG_VM_POISON
> u32 val;
> #endif
> };
>
> Then, instead of #ifdefs in each structure, you do:
>
> struct page {
> struct vm_poison poison_start;
> ... other gunk
> struct vm_poison poison_end;
> };
Agreed, I'll reword that in the next version.
Thanks,
Sasha
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-10-08 14:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-30 1:47 [PATCH 0/5] mm: poison critical mm/ structs Sasha Levin
2014-09-30 1:47 ` [PATCH 1/5] mm: add poisoning basics Sasha Levin
2014-09-30 1:47 ` [PATCH 2/5] mm: constify dump_page and friends Sasha Levin
2014-09-30 1:47 ` [PATCH 3/5] mm: poison mm_struct Sasha Levin
2014-09-30 1:47 ` [PATCH 4/5] mm: poison vm_area_struct Sasha Levin
2014-09-30 1:47 ` [PATCH 5/5] mm: poison page struct Sasha Levin
2014-10-07 22:02 ` Dave Hansen
2014-10-08 7:10 ` Christoph Lameter
2014-10-08 14:22 ` Sasha Levin [this message]
2014-10-01 21:07 ` [PATCH 0/5] mm: poison critical mm/ structs Andrew Morton
2014-10-01 21:39 ` Sasha Levin
2014-10-01 21:48 ` Andrew Morton
2014-10-02 3:51 ` Sasha Levin
2014-10-02 9:23 ` Hugh Dickins
2014-10-02 14:58 ` Sasha Levin
2014-10-07 22:16 ` Dave Hansen
2014-10-08 16:43 ` Sasha Levin
2014-10-02 15:13 ` Dave Jones
2014-10-09 19:11 ` Sasha Levin
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=543548C3.7030003@oracle.com \
--to=sasha.levin@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=dave.hansen@intel.com \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.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).