From: Jeff Moyer <jmoyer@redhat.com>
To: Justin He <Justin.He@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
Kirill A.Shutemov <kirill.shutemov@linux.intel.com>,
"linux-mm\@kvack.org" <linux-mm@kvack.org>
Subject: Re: bug: data corruption introduced by commit 83d116c53058 ("mm: fix double page fault on arm64 if PTE_AF is cleared")
Date: Tue, 11 Feb 2020 11:44:06 -0500 [thread overview]
Message-ID: <x49sgjhnkfd.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <VE1PR08MB4639EBB60C7196213652D1E6F7180@VE1PR08MB4639.eurprd08.prod.outlook.com> (Justin He's message of "Tue, 11 Feb 2020 04:29:49 +0000")
Hi, Justin,
Justin He <Justin.He@arm.com> writes:
>> Thanks for the report. But this commit 83d116c53058 doesn't add the
>> new clear_page code path. Besides the pte_mkyoung part, It just refines
>> the codes(no functional change) and add a WARN_ON_ONCE to indicate
>> there is any obscure case before.
>
> I can't reproduce it with your provided test file on my arm64 qemu with
> a pmem device.
> Could you do me a favor that just revert 83d116c53058 but keep that
> WARN_ON_ONCE after clear_page()? Is there any difference?
> Thanks for your help
Below is the patch I used to put the WARN_ON_ONCE after the clear_page,
just to be sure that's what you intended. So with 83d116c53058
reverted, and the below patch applied, the WARN_ON_ONCE does not
trigger.
-Jeff
diff --git a/mm/memory.c b/mm/memory.c
index 3bab0d3976ea..3fea34375c7f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2259,8 +2259,10 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
* in which case we just give up and fill the result with
* zeroes.
*/
- if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
+ if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
+ WARN_ON_ONCE(1);
clear_page(kaddr);
+ }
kunmap_atomic(kaddr);
flush_dcache_page(dst);
} else
next prev parent reply other threads:[~2020-02-11 16:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 22:51 bug: data corruption introduced by commit 83d116c53058 ("mm: fix double page fault on arm64 if PTE_AF is cleared") Jeff Moyer
2020-02-11 4:17 ` Justin He
2020-02-11 4:29 ` Justin He
2020-02-11 16:44 ` Jeff Moyer [this message]
2020-02-11 17:33 ` Kirill A. Shutemov
2020-02-11 17:55 ` Jeff Moyer
2020-02-11 21:44 ` Kirill A. Shutemov
2020-02-11 22:01 ` Jeff Moyer
2020-02-11 22:15 ` Kirill A. Shutemov
2020-02-11 14:51 ` Kirill A. Shutemov
2020-02-11 16:27 ` Jeff Moyer
2020-02-11 22:40 ` Kirill A. Shutemov
2020-02-12 14:22 ` Jeff Moyer
2020-02-13 12:14 ` Kirill A. Shutemov
2020-02-14 21:07 ` Jeff Moyer
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=x49sgjhnkfd.fsf@segfault.boston.devel.redhat.com \
--to=jmoyer@redhat.com \
--cc=Catalin.Marinas@arm.com \
--cc=Justin.He@arm.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-mm@kvack.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).