linux-kernel - Re: [PATCH v5 00/16] HWPOISON: soft offline rework

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Date:   Mon, 3 Aug 2020 11:19:09 -0400
From:   Qian Cai <cai@....pw>
To:     HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
Cc:     "nao.horiguchi@...il.com" <nao.horiguchi@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "mhocko@...nel.org" <mhocko@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "osalvador@...e.de" <osalvador@...e.de>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "aneesh.kumar@...ux.vnet.ibm.com" <aneesh.kumar@...ux.vnet.ibm.com>,
        "zeil@...dex-team.ru" <zeil@...dex-team.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 00/16] HWPOISON: soft offline rework

On Mon, Aug 03, 2020 at 01:36:58PM +0000, HORIGUCHI NAOYA(堀口 直也) wrote:
> Hello,
> 
> On Mon, Aug 03, 2020 at 08:39:55AM -0400, Qian Cai wrote:
> > On Fri, Jul 31, 2020 at 12:20:56PM +0000, nao.horiguchi@...il.com wrote:
> > > This patchset is the latest version of soft offline rework patchset
> > > targetted for v5.9.
> > > 
> > > Main focus of this series is to stabilize soft offline.  Historically soft
> > > offlined pages have suffered from racy conditions because PageHWPoison is
> > > used to a little too aggressively, which (directly or indirectly) invades
> > > other mm code which cares little about hwpoison.  This results in unexpected
> > > behavior or kernel panic, which is very far from soft offline's "do not
> > > disturb userspace or other kernel component" policy.
> > > 
> > > Main point of this change set is to contain target page "via buddy allocator",
> > > where we first free the target page as we do for normal pages, and remove
> > > from buddy only when we confirm that it reaches free list. There is surely
> > > race window of page allocation, but that's fine because someone really want
> > > that page and the page is still working, so soft offline can happily give up.
> > > 
> > > v4 from Oscar tries to handle the race around reallocation, but that part
> > > seems still work in progress, so I decide to separate it for changes into
> > > v5.9.  Thank you for your contribution, Oscar.
> > > 
> > > The issue reported by Qian Cai is fixed by patch 16/16.
> > 
> > I am still getting EIO everywhere on next-20200803 (which includes this v5).
> > 
> > # ./random 1
> > - start: migrate_huge_offline
> > - use NUMA nodes 0,8.
> > - mmap and free 8388608 bytes hugepages on node 0
> > - mmap and free 8388608 bytes hugepages on node 8
> > madvise: Input/output error
> > 
> > From the serial console,
> > 
> > [  637.164222][ T8357] soft offline: 0x118ee0: hugepage isolation failed: 0, page count 2, type 7fff800001000e (referenced|uptodate|dirty|head)
> > [  637.164890][ T8357] Soft offlining pfn 0x20001380 at process virtual address 0x7fff9f000000
> > [  637.165422][ T8357] Soft offlining pfn 0x3ba00 at process virtual address 0x7fff9f200000
> > [  637.166409][ T8357] Soft offlining pfn 0x201914a0 at process virtual address 0x7fff9f000000
> > [  637.166833][ T8357] Soft offlining pfn 0x12b9a0 at process virtual address 0x7fff9f200000
> > [  637.168044][ T8357] Soft offlining pfn 0x1abb60 at process virtual address 0x7fff9f000000
> > [  637.168557][ T8357] Soft offlining pfn 0x20014820 at process virtual address 0x7fff9f200000
> > [  637.169493][ T8357] Soft offlining pfn 0x119720 at process virtual address 0x7fff9f000000
> > [  637.169603][ T8357] soft offline: 0x119720: hugepage isolation failed: 0, page count 2, type 7fff800001000e (referenced|uptodate|dirty|head)
> > [  637.169756][ T8357] Soft offlining pfn 0x118ee0 at process virtual address 0x7fff9f200000
> > [  637.170653][ T8357] Soft offlining pfn 0x200e81e0 at process virtual address 0x7fff9f000000
> > [  637.171067][ T8357] Soft offlining pfn 0x201c5f60 at process virtual address 0x7fff9f200000
> > [  637.172101][ T8357] Soft offlining pfn 0x201c8f00 at process virtual address 0x7fff9f000000
> > [  637.172241][ T8357] __get_any_page: 0x201c8f00: unknown zero refcount page type 87fff8000000000
> 
> I might misjudge to skip the following patch, sorry about that.
> Could you try with it?

Still getting EIO after applied this patch.

[ 1215.499030][T88982] soft offline: 0x201bdc20: hugepage isolation failed: 0, page count 2, type 87fff800001000e (referenced|uptodate|dirty|head)
[ 1215.499775][T88982] Soft offlining pfn 0x201bdc20 at process virtual address 0x7fff91a00000
[ 1215.500189][T88982] Soft offlining pfn 0x201c19c0 at process virtual address 0x7fff91c00000
[ 1215.500297][T88982] soft offline: 0x201c19c0: hugepage isolation failed: 0, page count 2, type 87fff800001000e (referenced|uptodate|dirty|head)
[ 1215.500982][T88982] Soft offlining pfn 0x1f1fa0 at process virtual address 0x7fff91a00000
[ 1215.501086][T88982] soft offline: 0x1f1fa0: hugepage isolation failed: 0, page count 2, type 7fff800001000e (referenced|uptodate|dirty|head)
[ 1215.501237][T88982] Soft offlining pfn 0x1f4520 at process virtual address 0x7fff91c00000
[ 1215.501355][T88982] soft offline: 0x1f4520: hugepage isolation failed: 0, page count 2, type 7fff800001000e (referenced|uptodate|dirty|head)
[ 1215.502196][T88982] Soft offlining pfn 0x1f4520 at process virtual address 0x7fff91a00000
[ 1215.502573][T88982] Soft offlining pfn 0x1f1fa0 at process virtual address 0x7fff91c00000
[ 1215.502687][T88982] soft offline: 0x1f1fa0: hugepage isolation failed: 0, page count 2, type 7fff800001000e (referenced|uptodate|dirty|head)
[ 1215.503245][T88982] Soft offlining pfn 0x201c3cc0 at process virtual address 0x7fff91a00000
[ 1215.503594][T88982] Soft offlining pfn 0x201c3ce0 at process virtual address 0x7fff91c00000
[ 1215.503755][T88982] __get_any_page: 0x201c3ce0: unknown zero refcount page type 87fff8000000000

> 
> ---
> From eafe6fde94cd15e67631540f1b2b000b6e33a650 Mon Sep 17 00:00:00 2001
> From: Oscar Salvador <osalvador@...e.de>
> Date: Mon, 3 Aug 2020 22:25:10 +0900
> Subject: [PATCH] mm,hwpoison: Drain pcplists before bailing out for non-buddy
>  zero-refcount page