linux-kernel - Re: [PATCH v3 0/5] HWpoison: further fixes and cleanups

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Message-ID: <9bd7ac81968a7897474804d53bfc1286@suse.de>
Date:   Wed, 16 Sep 2020 18:30:56 +0200
From:   osalvador@...e.de
To:     Aristeu Rozanski <aris@...vo.org>
Cc:     naoya.horiguchi@....com, akpm@...ux-foundation.org,
        mhocko@...nel.org, tony.luck@...el.com, cai@....pw,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 0/5] HWpoison: further fixes and cleanups

On 2020-09-16 16:46, Aristeu Rozanski wrote:
> Hi Oscar,
> 
> On Wed, Sep 16, 2020 at 04:09:30PM +0200, Oscar Salvador wrote:
>> On Wed, Sep 16, 2020 at 09:53:58AM -0400, Aristeu Rozanski wrote:
>> Can you try the other patch I posted in response to Naoya?
> 
> Same thing:
> 
> [  369.195056] Soft offlining pfn 0x3fb5bf at process virtual address
> 0x7ffc84350000
> [  369.195073] page:000000002bb131e4 refcount:1 mapcount:0
> mapping:0000000000000000 index:0x7ffc8435 pfn:0x3fb5bf
> [  369.195080] anon flags:
> 0x3ffff80008000e(referenced|uptodate|dirty|swapbacked)
> [  369.202131] raw: 003ffff80008000e 5deadbeef0000100 5deadbeef0000122
> c000003fda1c7431
> [  369.202137] raw: 000000007ffc8435 0000000000000000 00000001ffffffff
> c000003fd63af000
> [  369.202141] page dumped because: page_handle_poison
> [  369.202145] page->mem_cgroup:c000003fd63af000
> [  369.215055] page_handle_poison: hugepage_or_freepage failed�n
> [  369.215057] __soft_offline_page: page_handle_poison -EBUSY
> [  369.215068] page:000000002bb131e4 refcount:3 mapcount:0
> mapping:00000000f6ca3f32 index:0x5c pfn:0x3fb5bf
> [  369.215110] aops:xfs_address_space_operations [xfs] ino:49f9c5f
> dentry name:"messages"
> [  369.215117] flags: 0x3ffff800002008(dirty|private)
> [  369.215121] raw: 003ffff800002008 5deadbeef0000100 5deadbeef0000122
> c000003fadd3daa8
> [  369.215127] raw: 000000000000005c c000003fd9497c20 00000003ffffffff
> c000003fd1143000
> [  369.215132] page dumped because: __soft_offline_page after migrate
> [  369.215136] page->mem_cgroup:c000003fd1143000


Ok, this is something different.
The race you saw previously is kinda normal as there is a race window 
between spotting a freepage and taking it off the buddy freelists.
The retry patch should help there.

The issue you are seeing right here is due to the call to 
page_handle_poison in __soft_offline_page being wrong, as we pass 
hugepage_or_freepage = true inconditionally, which is wrong.

Should be: