From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Kyungtae Kim <kt0755@gmail.com>,
akpm@linux-foundation.org, pavel.tatashin@microsoft.com,
osalvador@suse.de, rppt@linux.vnet.ibm.com, aaron.lu@intel.com,
iamjoonsoo.kim@lge.com, alexander.h.duyck@linux.intel.com,
mgorman@techsingularity.net, lifeasageek@gmail.com,
threeearcat@gmail.com, syzkaller@googlegroups.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Subject: Re: UBSAN: Undefined behaviour in mm/page_alloc.c
Date: Fri, 9 Nov 2018 11:22:35 +0100 [thread overview]
Message-ID: <20181109102235.GD5321@dhcp22.suse.cz> (raw)
In-Reply-To: <d8757554-45f4-1240-dc8a-0f918ae0e5f3@suse.cz>
On Fri 09-11-18 11:10:00, Vlastimil Babka wrote:
> On 11/9/18 10:56 AM, Michal Hocko wrote:
> > On Fri 09-11-18 18:41:53, Tetsuo Handa wrote:
> >> On 2018/11/09 17:43, Michal Hocko wrote:
> >>> @@ -4364,6 +4353,17 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
> >>> gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
> >>> struct alloc_context ac = { };
> >>>
> >>> + /*
> >>> + * In the slowpath, we sanity check order to avoid ever trying to
> >>
> >> Please keep the comment up to dated.
> >
> > Does this following look better?
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 9fc10a1029cf..bf9aecba4222 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -4354,10 +4354,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
> > struct alloc_context ac = { };
> >
> > /*
> > - * In the slowpath, we sanity check order to avoid ever trying to
> > - * reclaim >= MAX_ORDER areas which will never succeed. Callers may
> > - * be using allocators in order of preference for an area that is
> > - * too large.
> > + * There are several places where we assume that the order value is sane
> > + * so bail out early if the request is out of bound.
> > */
> > if (order >= MAX_ORDER) {
> > WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
>
> Looks ok, but I'd add unlikely(), although it doesn't currently seem to
> make any difference.
>
> You can add Acked-by: Vlastimil Babka <vbabka@suse.cz>
OK, I have added both. Thanks!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-11-09 10:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-09 4:09 UBSAN: Undefined behaviour in mm/page_alloc.c Kyungtae Kim
2018-11-09 8:42 ` Vlastimil Babka
2018-11-09 8:43 ` Michal Hocko
2018-11-09 9:41 ` Tetsuo Handa
2018-11-09 9:56 ` Michal Hocko
2018-11-09 10:07 ` Tetsuo Handa
2018-11-09 10:25 ` Michal Hocko
2018-11-09 10:10 ` Vlastimil Babka
2018-11-09 10:22 ` Michal Hocko [this message]
2018-11-09 10:24 ` Tetsuo Handa
2018-11-09 10:28 ` Michal Hocko
2018-11-09 10:52 ` Balbir Singh
2018-11-09 9:56 ` Mel Gorman
2018-11-13 9:43 ` Michal Hocko
2018-11-13 23:15 ` Andrew Morton
2018-11-13 23:23 ` Vlastimil Babka
2018-11-13 23:32 ` Andrew Morton
2018-11-14 0:05 ` Vlastimil Babka
2018-11-19 23:57 ` Pavel Machek
2018-11-13 23:29 ` Andrew Morton
2018-11-14 7:10 ` Michal Hocko
2018-11-16 23:43 ` Dmitry Vyukov
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=20181109102235.GD5321@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=aaron.lu@intel.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.h.duyck@linux.intel.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=khlebnikov@yandex-team.ru \
--cc=kt0755@gmail.com \
--cc=lifeasageek@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=osalvador@suse.de \
--cc=pavel.tatashin@microsoft.com \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=rppt@linux.vnet.ibm.com \
--cc=syzkaller@googlegroups.com \
--cc=threeearcat@gmail.com \
--cc=vbabka@suse.cz \
/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).