From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx134.postini.com [74.125.245.134]) by kanga.kvack.org (Postfix) with SMTP id E43096B0032 for ; Thu, 22 Aug 2013 19:34:58 -0400 (EDT) Received: from /spool/local by e28smtp04.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 23 Aug 2013 04:56:55 +0530 Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id CA759E0054 for ; Fri, 23 Aug 2013 05:05:23 +0530 (IST) Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r7MNaOZ231654112 for ; Fri, 23 Aug 2013 05:06:25 +0530 Received: from d28av03.in.ibm.com (localhost [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r7MNYpRO010163 for ; Fri, 23 Aug 2013 05:04:52 +0530 Date: Fri, 23 Aug 2013 07:34:50 +0800 From: Wanpeng Li Subject: Re: [PATCH 1/6] mm/hwpoison: fix lose PG_dirty flag for errors on mlocked pages Message-ID: <20130822233450.GA17834@hacker.(null)> Reply-To: Wanpeng Li References: <1377164907-24801-1-git-send-email-liwanp@linux.vnet.ibm.com> <1377186692-rqporagm-mutt-n-horiguchi@ah.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1377186692-rqporagm-mutt-n-horiguchi@ah.jp.nec.com> Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: Andrew Morton , Andi Kleen , Fengguang Wu , Tony Luck , gong.chen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi Naoya, On Thu, Aug 22, 2013 at 11:51:32AM -0400, Naoya Horiguchi wrote: >Hi Wanpeng, > >On Thu, Aug 22, 2013 at 05:48:22PM +0800, Wanpeng Li wrote: >> memory_failure() store the page flag of the error page before doing unmap, >> and (only) if the first check with page flags at the time decided the error >> page is unknown, it do the second check with the stored page flag since >> memory_failure() does unmapping of the error pages before doing page_action(). >> This unmapping changes the page state, especially page_remove_rmap() (called >> from try_to_unmap_one()) clears PG_mlocked, so page_action() can't catch >> mlocked pages after that. >> >> However, memory_failure() can't handle memory errors on dirty mlocked pages >> correctly. try_to_unmap_one will move the dirty bit from pte to the physical >> page, the second check lose it since it check the stored page flag. This patch >> fix it by restore PG_dirty flag to stored page flag if the page is dirty. > >Right. And I'm guessing that the discrepancy between pte_dirty and PageDirty >can happen on the situations rather than mlocked pages. >Anyway, using both of page flags before and after unmapping looks right to me. > The first check is p->flags which will contain PG_dirty flags if pte_dirty is set. The second check which introduced by commit 524fca1e(HWPOISON: fix misjudgement of page_action() for errors on mlocked pages) is just for mlock page case. >Reviewed-by: Naoya Horiguchi > Thanks for your review and quick feedback. ;-) Regards, Wanpeng Li > >> Testcase: >> >> #define _GNU_SOURCE >> #include >> #include >> #include >> #include >> #include >> >> #define PAGES_TO_TEST 2 >> #define PAGE_SIZE 4096 >> >> int main(void) >> { >> char *mem; >> int i; >> >> mem = mmap(NULL, PAGES_TO_TEST * PAGE_SIZE, >> PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_LOCKED, 0, 0); >> >> for (i = 0; i < PAGES_TO_TEST; i++) >> mem[i * PAGE_SIZE] = 'a'; >> >> if (madvise(mem, PAGES_TO_TEST * PAGE_SIZE, MADV_HWPOISON) == -1) >> return -1; >> >> return 0; >> } >> >> Before patch: >> >> [ 912.839247] Injecting memory failure for page 7dfb8 at 7f6b4e37b000 >> [ 912.839257] MCE 0x7dfb8: clean mlocked LRU page recovery: Recovered >> [ 912.845550] MCE 0x7dfb8: clean mlocked LRU page still referenced by 1 users >> [ 912.852586] Injecting memory failure for page 7e6aa at 7f6b4e37c000 >> [ 912.852594] MCE 0x7e6aa: clean mlocked LRU page recovery: Recovered >> [ 912.858936] MCE 0x7e6aa: clean mlocked LRU page still referenced by 1 users >> >> After patch: >> >> [ 163.590225] Injecting memory failure for page 91bc2f at 7f9f5b0e5000 >> [ 163.590264] MCE 0x91bc2f: dirty mlocked LRU page recovery: Recovered >> [ 163.596680] MCE 0x91bc2f: dirty mlocked LRU page still referenced by 1 users >> [ 163.603831] Injecting memory failure for page 91cdd3 at 7f9f5b0e6000 >> [ 163.603852] MCE 0x91cdd3: dirty mlocked LRU page recovery: Recovered >> [ 163.610305] MCE 0x91cdd3: dirty mlocked LRU page still referenced by 1 users >> >> Signed-off-by: Wanpeng Li >> --- >> mm/memory-failure.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index bee58d8..e156084 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -1206,6 +1206,9 @@ int memory_failure(unsigned long pfn, int trapno, int flags) >> for (ps = error_states;; ps++) >> if ((p->flags & ps->mask) == ps->res) >> break; >> + >> + page_flags |= (p->flags & (1UL << PG_dirty)); >> + >> if (!ps->mask) >> for (ps = error_states;; ps++) >> if ((page_flags & ps->mask) == ps->res) >> -- >> 1.7.7.6 >> > >-- >To unsubscribe, send a message with 'unsubscribe linux-mm' in >the body to majordomo@kvack.org. For more info on Linux MM, >see: http://www.linux-mm.org/ . >Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org