From: Gavin Shan <gshan@redhat.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
will@kernel.org, akpm@linux-foundation.org, chuhu@redhat.com,
shan.gavin@gmail.com
Subject: Re: [PATCH v3 12/12] mm/debug_vm_pgtable: Fix corrupted page flag
Date: Wed, 21 Jul 2021 22:03:39 +1000 [thread overview]
Message-ID: <8157142c-58e0-44c4-5cdb-76fff4a07210@redhat.com> (raw)
In-Reply-To: <57cb2f04-b3f2-2df4-3d9b-0b430b9c9f3e@arm.com>
Hi Anshuman,
On 7/21/21 8:18 PM, Anshuman Khandual wrote:
> On 7/19/21 6:36 PM, Gavin Shan wrote:
>> In page table entry modifying tests, set_xxx_at() are used to populate
>> the page table entries. On ARM64, PG_arch_1 is set to the target page
>> flag if execution permission is given. The page flag is kept when the
>> page is free'd to buddy's free area list. However, it will trigger page
>> checking failure when it's pulled from the buddy's free area list, as
>> the following warning messages indicate.
>>
>> BUG: Bad page state in process memhog pfn:08000
>> page:0000000015c0a628 refcount:0 mapcount:0 \
>> mapping:0000000000000000 index:0x1 pfn:0x8000
>> flags: 0x7ffff8000000800(arch_1|node=0|zone=0|lastcpupid=0xfffff)
>> raw: 07ffff8000000800 dead000000000100 dead000000000122 0000000000000000
>> raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
>> page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag(s) set
>>
>> This fixes the issue by clearing PG_arch_1 through flush_dcache_page()
>> after set_xxx_at() is called.
>
> Could you please add comments before each flush_dcache_page() instance
> explaining why this is needed for arm64 platforms with relevant PG_arch_1
> context and how this does not have any adverse effect on other platforms ?
> It should be easy for some one looking at this code after a while to figure
> out from where flush_dcache_page() came from.
>
Good point. I will improve chage log to include the commit ID in v4 where the
page flag (PG_arch_1) is used and explain how. In that case, it's much clearer
to understand the reason why we need flush_dcache_page() after set_xxx_at() on
ARM64.
Thanks,
Gavin
next prev parent reply other threads:[~2021-07-21 12:04 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 13:06 [PATCH v3 00/12] mm/debug_vm_pgtable: Enhancements Gavin Shan
2021-07-19 13:06 ` [PATCH v3 01/12] mm/debug_vm_pgtable: Introduce struct pgtable_debug_args Gavin Shan
2021-07-21 5:44 ` Anshuman Khandual
2021-07-21 10:20 ` Gavin Shan
2021-07-21 10:39 ` Anshuman Khandual
2021-07-21 10:59 ` Anshuman Khandual
2021-07-21 11:59 ` Gavin Shan
2021-07-22 4:41 ` Anshuman Khandual
2021-07-22 6:23 ` Gavin Shan
2021-07-22 7:08 ` Anshuman Khandual
2021-07-23 0:43 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 02/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in basic tests Gavin Shan
2021-07-21 5:57 ` Anshuman Khandual
2021-07-21 11:57 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 03/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in leaf and savewrite tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 04/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in protnone and devmap tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 05/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in soft_dirty and swap tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 06/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in migration and thp tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 07/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PTE modifying tests Gavin Shan
2021-07-22 5:56 ` Anshuman Khandual
2021-07-22 6:37 ` Gavin Shan
2021-07-23 2:39 ` Anshuman Khandual
2021-07-23 4:23 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PMD " Gavin Shan
2021-07-22 5:45 ` Anshuman Khandual
2021-07-22 6:41 ` Gavin Shan
2021-07-22 7:11 ` Anshuman Khandual
2021-07-23 1:00 ` Gavin Shan
2021-07-23 2:33 ` Anshuman Khandual
2021-07-19 13:06 ` [PATCH v3 09/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PUD " Gavin Shan
2021-07-22 5:39 ` Anshuman Khandual
2021-07-22 6:47 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 10/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PGD and P4D " Gavin Shan
2021-07-22 5:09 ` Anshuman Khandual
2021-07-22 6:50 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 11/12] mm/debug_vm_pgtable: Remove unused code Gavin Shan
2021-07-22 4:51 ` Anshuman Khandual
2021-07-22 6:53 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 12/12] mm/debug_vm_pgtable: Fix corrupted page flag Gavin Shan
2021-07-21 10:18 ` Anshuman Khandual
2021-07-21 12:03 ` Gavin Shan [this message]
2021-07-22 3:51 ` Anshuman Khandual
2021-07-22 6:54 ` Gavin Shan
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=8157142c-58e0-44c4-5cdb-76fff4a07210@redhat.com \
--to=gshan@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=catalin.marinas@arm.com \
--cc=chuhu@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=shan.gavin@gmail.com \
--cc=will@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.