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From: Andrew Morton <firstname.lastname@example.org>
To: Miaohe Lin <email@example.com>
Cc: "HORIGUCHI NAOYA" <firstname.lastname@example.org>,
Subject: Re: [PATCH 3/3] mm/memory_hotplug: make HWPoisoned dirty swapcache pages unmovable
Date: Thu, 4 Nov 2021 15:07:17 -0700 [thread overview]
Message-ID: <email@example.com> (raw)
On Mon, 23 Aug 2021 17:14:29 +0800 Miaohe Lin <firstname.lastname@example.org> wrote:
> On 2021/8/23 16:26, HORIGUCHI NAOYA(堀口 直也) wrote:
> > On Sat, Aug 21, 2021 at 05:42:46PM +0800, Miaohe Lin wrote:
> >> HWPoisoned dirty swapcache pages are kept for killing owner processes.
> >> We should not offline these pages or do_swap_page() would access the
> >> offline pages and lead to bad ending.
> > Thank you for the report. I'm not yet sure of the whole picture of this
> > issue. do_swap_page() is expected to return with fault VM_FAULT_HWPOISON
> > when called via the access to the error page, so I wonder why this doesn't
> > work for your situation. And what is the "bad ending" in the description?
> IMO we might hotremove the page while SwapCache still have ref to it. Thus the page
> struct would be accessed after offlined. The page struct should be invalid in this case
> and this would make do_swap_page fragile. Or am I miss something?
> > I feel that aborting memory hotremove due to a hwpoisoned dirty swapcache
> > might be too hard, so I'd like to find another solution if we have.
> If there is a better way, we can just drop this one.
> Many thanks for your review and reply! :)
> > # You may separate this patch from former two to make them merged to
> > # mainline soon.
> >> --- a/mm/memory_hotplug.c
> >> +++ b/mm/memory_hotplug.c
> >> @@ -1664,6 +1664,12 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
> >> */
> >> if (PageOffline(page) && page_count(page))
> >> return -EBUSY;
> >> + /*
> >> + * HWPoisoned dirty swapcache pages are definitely unmovable
> >> + * because they are kept for killing owner processes.
> >> + */
> >> + if (PageHWPoison(page) && PageSwapCache(page))
> >> + return -EBUSY;
I'll drop this. Please resend something if you still believe that
changes are desirable.
prev parent reply other threads:[~2021-11-04 22:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-21 9:42 [PATCH 0/3] Cleanup and fixups for memory hotplug Miaohe Lin
2021-08-21 9:42 ` [PATCH 1/3] mm/memory_hotplug: use helper zone_is_zone_device() to simplify the code Miaohe Lin
2021-08-23 8:20 ` HORIGUCHI NAOYA(堀口 直也)
2021-08-23 9:11 ` Oscar Salvador
2021-08-23 12:14 ` David Hildenbrand
2021-08-21 9:42 ` [PATCH 2/3] mm/memory_hotplug: fix potential permanent lru cache disable Miaohe Lin
2021-08-23 8:21 ` HORIGUCHI NAOYA(堀口 直也)
2021-08-23 9:15 ` Oscar Salvador
2021-08-23 11:13 ` Miaohe Lin
2021-08-23 12:15 ` David Hildenbrand
2021-08-21 9:42 ` [PATCH 3/3] mm/memory_hotplug: make HWPoisoned dirty swapcache pages unmovable Miaohe Lin
2021-08-23 8:26 ` HORIGUCHI NAOYA(堀口 直也)
2021-08-23 9:14 ` Miaohe Lin
2021-11-04 22:07 ` Andrew Morton [this message]
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