From: Qian Cai <cai@lca.pw>
To: Michal Hocko <mhocko@kernel.org>
Cc: akpm@linux-foundation.org, mingo@kernel.org, hpa@zytor.com,
mgorman@techsingularity.net, tglx@linutronix.de,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: skip checking poison pattern for page_to_nid()
Date: Wed, 19 Dec 2018 07:46:49 -0500 [thread overview]
Message-ID: <cbfacb4b-dbfd-f68f-3d1e-05e137feca18@lca.pw> (raw)
In-Reply-To: <20181219102010.GF5758@dhcp22.suse.cz>
On 12/19/18 5:20 AM, Michal Hocko wrote:
> On Tue 18-12-18 20:57:32, Qian Cai wrote:
> [...]
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index 5411de93a363..f083f366ea90 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -985,9 +985,7 @@ extern int page_to_nid(const struct page *page);
>> #else
>> static inline int page_to_nid(const struct page *page)
>> {
>> - struct page *p = (struct page *)page;
>> -
>> - return (PF_POISONED_CHECK(p)->flags >> NODES_PGSHIFT) & NODES_MASK;
>> + return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
>> }
>> #endif
>
> I didn't get to think about a proper fix but this is clearly worng. If
> the page is still poisoned then flags are clearly bogus and the node you
> get is a garbage as well. Have you actually tested this patch?
>
Yes, I did notice that after running for a while triggering some UBSAN
out-of-bounds access warnings. I am still trying to figure out how those
uninitialized page flags survived though after
mm_init
mem_init
memblock_free_all
init_single_page()
next prev parent reply other threads:[~2018-12-19 12:46 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1545172285.18411.26.camel@lca.pw>
2018-12-19 1:57 ` [PATCH] mm: skip checking poison pattern for page_to_nid() Qian Cai
2018-12-19 10:20 ` Michal Hocko
2018-12-19 12:46 ` Qian Cai [this message]
2018-12-20 6:03 ` [PATCH] mm/page_owner: fix for deferred struct page init Qian Cai
2018-12-20 9:22 ` Michal Hocko
2018-12-20 18:50 ` [PATCH v2] " Qian Cai
2018-12-20 20:31 ` [PATCH v3] " Qian Cai
2018-12-20 21:00 ` William Kucharski
2018-12-20 21:04 ` Qian Cai
2019-01-03 11:51 ` Michal Hocko
2019-01-03 16:38 ` Qian Cai
2019-01-03 16:59 ` Michal Hocko
2019-01-03 17:38 ` Qian Cai
2019-01-03 19:07 ` Michal Hocko
2019-01-03 19:53 ` Qian Cai
2019-01-03 20:22 ` Michal Hocko
2019-01-03 22:22 ` Qian Cai
2019-01-04 13:09 ` Michal Hocko
2019-01-04 15:01 ` Qian Cai
2019-01-04 15:17 ` Michal Hocko
2019-01-04 15:25 ` Qian Cai
2019-01-04 15:32 ` Michal Hocko
2019-01-04 20:18 ` Qian Cai
2019-01-07 18:43 ` Michal Hocko
2019-01-08 1:53 ` Qian Cai
2019-01-08 8:20 ` Michal Hocko
2019-01-08 13:19 ` Qian Cai
2019-01-08 22:02 ` Andrew Morton
2019-01-08 22:13 ` Qian Cai
2019-01-08 22:40 ` Michal Hocko
2019-01-09 7:34 ` [PATCH v2] " Michal Hocko
2019-01-15 20:28 ` [PATCH] Revert "mm: use early_pfn_to_nid in page_ext_init" Qian Cai
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