From: Denys Vlasenko <dvlasenk@redhat.com>
To: Will Deacon <will@kernel.org>, Liu Shixin <liushixin2@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
David Hildenbrand <dhildenb@redhat.com>,
Rafael Aquini <raquini@redhat.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] arm64/mm: fix incorrect file_map_count for invalid pmd
Date: Mon, 28 Nov 2022 17:26:14 +0100 [thread overview]
Message-ID: <954658fd-dc20-e5f1-78b1-a70b064f7993@redhat.com> (raw)
In-Reply-To: <20221121181859.GE7645@willie-the-truck>
On 11/21/22 19:18, Will Deacon wrote:
> On Mon, Nov 21, 2022 at 03:36:08PM +0800, Liu Shixin wrote:
>> The page table check trigger BUG_ON() unexpectedly when split hugepage:
>>
>> ------------[ cut here ]------------
>> kernel BUG at mm/page_table_check.c:119!
>> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
>> Dumping ftrace buffer:
>> (ftrace buffer empty)
>> Modules linked in:
>> CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748
>> Hardware name: linux,dummy-virt (DT)
>> pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> pc : page_table_check_set.isra.0+0x398/0x468
>> lr : page_table_check_set.isra.0+0x1c0/0x468
>> [...]
>> Call trace:
>> page_table_check_set.isra.0+0x398/0x468
>> __page_table_check_pte_set+0x160/0x1c0
>> __split_huge_pmd_locked+0x900/0x1648
>> __split_huge_pmd+0x28c/0x3b8
>> unmap_page_range+0x428/0x858
>> unmap_single_vma+0xf4/0x1c8
>> zap_page_range+0x2b0/0x410
>> madvise_vma_behavior+0xc44/0xe78
>> do_madvise+0x280/0x698
>> __arm64_sys_madvise+0x90/0xe8
>> invoke_syscall.constprop.0+0xdc/0x1d8
>> do_el0_svc+0xf4/0x3f8
>> el0_svc+0x58/0x120
>> el0t_64_sync_handler+0xb8/0xc0
>> el0t_64_sync+0x19c/0x1a0
>> [...]
>>
>> On arm64, pmd_leaf() will return true even if the pmd is invalid due to
>> pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count
>> will not only decrease once but also increase once. Then in set_pte_at(),
>> the file_map_count increase again, and so trigger BUG_ON() unexpectedly.
>>
>> Add !pmd_present_invalid() check in pmd_user_accessible_page() to fix the
>> problem.
>>
>> Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
>> Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
>> Signed-off-by: Liu Shixin <liushixin2@huawei.com>
>> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
>> Acked-by: David Hildenbrand <david@redhat.com>
>> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>> v1->v2: Update comment and optimize the code by moving p?d_valid() at
>> first place suggested by Mark.
>> v2->v3: Replace pmd_valid() with pmd_present_invalid() suggested by Will.
>>
>> arch/arm64/include/asm/pgtable.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index edf6625ce965..17afb09f386f 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -863,7 +863,7 @@ static inline bool pte_user_accessible_page(pte_t pte)
>>
>> static inline bool pmd_user_accessible_page(pmd_t pmd)
>> {
>> - return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
>> + return pmd_leaf(pmd) && !pmd_present_invalid(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
>> }
>
> Acked-by: Will Deacon <will@kernel.org>
>
> But please see my comment on v2 about pud_user_exec() for the PUD case.
Can you be more specific? Do you ask for pud_user_exec() to be defined
and used here? Or something else?
Until this patch lands, amd64 PAGE_TABLE_CHECK + THP remains broken...
next prev parent reply other threads:[~2022-11-28 16:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 7:36 [PATCH v3] arm64/mm: fix incorrect file_map_count for invalid pmd Liu Shixin
2022-11-21 18:18 ` Will Deacon
2022-11-28 16:26 ` Denys Vlasenko [this message]
2022-11-29 14:26 ` Will Deacon
2023-01-05 18:03 ` Will Deacon
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=954658fd-dc20-e5f1-78b1-a70b064f7993@redhat.com \
--to=dvlasenk@redhat.com \
--cc=anshuman.khandual@arm.com \
--cc=catalin.marinas@arm.com \
--cc=dhildenb@redhat.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=liushixin2@huawei.com \
--cc=pasha.tatashin@soleen.com \
--cc=raquini@redhat.com \
--cc=wangkefeng.wang@huawei.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 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).