Messages in this thread | | | Subject | Re: memory offline infinite loop after soft offline | From | David Hildenbrand <> | Date | Thu, 17 Oct 2019 12:03:47 +0200 |
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On 17.10.19 12:01, Michal Hocko wrote: > On Thu 17-10-19 09:34:10, Naoya Horiguchi wrote: >> On Mon, Oct 14, 2019 at 10:39:14AM +0200, Michal Hocko wrote: > [...] >>> diff --git a/mm/page_isolation.c b/mm/page_isolation.c >>> index 89c19c0feadb..5fb3fee16fde 100644 >>> --- a/mm/page_isolation.c >>> +++ b/mm/page_isolation.c >>> @@ -274,7 +274,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, >>> * simple way to verify that as VM_BUG_ON(), though. >>> */ >>> pfn += 1 << page_order(page); >>> - else if (skip_hwpoisoned_pages && PageHWPoison(page)) >>> + else if (skip_hwpoisoned_pages && PageHWPoison(compound_head(page))) >>> /* A HWPoisoned page cannot be also PageBuddy */ >>> pfn++; >>> else >> >> This fix looks good to me. The original code only addresses hwpoisoned 4kB-page, >> we seem to have this issue since the following commit, > > Thanks a lot for double checking Naoya! > >> commit b023f46813cde6e3b8a8c24f432ff9c1fd8e9a64 >> Author: Wen Congyang <wency@cn.fujitsu.com> >> Date: Tue Dec 11 16:00:45 2012 -0800 >> >> memory-hotplug: skip HWPoisoned page when offlining pages >> >> and extension of LTP coverage finally discovered this. > > Qian, could you give the patch some testing? > --- > > From 441a9515dcdb29bb0ca39ff995632907d959032f Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Thu, 17 Oct 2019 11:49:15 +0200 > Subject: [PATCH] hugetlb, memory_hotplug: fix HWPoisoned tail pages properly > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > Qian Cai has noticed that hwpoisoned hugetlb pages prevent memory > offlining from making a forward progress. He has nailed down the issue > to be __test_page_isolated_in_pageblock always returning EBUSY because > of soft offlined page: > [ 101.665160][ T8885] pfn = 77501, end_pfn = 78000 > [ 101.665245][ T8885] page:c00c000001dd4040 refcount:0 mapcount:0 > mapping:0000000000000000 index:0x0 > [ 101.665329][ T8885] flags: 0x3fffc000000000() > [ 101.665391][ T8885] raw: 003fffc000000000 0000000000000000 ffffffff01dd0500 > 0000000000000000 > [ 101.665498][ T8885] raw: 0000000000000000 0000000000000000 00000000ffffffff > 0000000000000000 > [ 101.665588][ T8885] page dumped because: soft_offline > [ 101.665639][ T8885] page_owner tracks the page as freed > [ 101.665697][ T8885] page last allocated via order 5, migratetype Movable, > gfp_mask > 0x346cca(GFP_HIGHUSER_MOVABLE|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP|__GFP_ > THISNODE) > [ 101.665924][ T8885] prep_new_page+0x3c0/0x440 > [ 101.665962][ T8885] get_page_from_freelist+0x2568/0x2bb0 > [ 101.666059][ T8885] __alloc_pages_nodemask+0x1b4/0x670 > [ 101.666115][ T8885] alloc_fresh_huge_page+0x244/0x6e0 > [ 101.666183][ T8885] alloc_migrate_huge_page+0x30/0x70 > [ 101.666254][ T8885] alloc_new_node_page+0xc4/0x380 > [ 101.666325][ T8885] migrate_pages+0x3b4/0x19e0 > [ 101.666375][ T8885] do_move_pages_to_node.isra.29.part.30+0x44/0xa0 > [ 101.666464][ T8885] kernel_move_pages+0x498/0xfc0 > [ 101.666520][ T8885] sys_move_pages+0x28/0x40 > [ 101.666643][ T8885] system_call+0x5c/0x68 > [ 101.666665][ T8885] page last free stack trace: > [ 101.666704][ T8885] __free_pages_ok+0xa4c/0xd40 > [ 101.666773][ T8885] update_and_free_page+0x2dc/0x5b0 > [ 101.666821][ T8885] free_huge_page+0x2dc/0x740 > [ 101.666875][ T8885] __put_compound_page+0x64/0xc0 > [ 101.666926][ T8885] putback_active_hugepage+0x228/0x390 > [ 101.666990][ T8885] migrate_pages+0xa78/0x19e0 > [ 101.667048][ T8885] soft_offline_page+0x314/0x1050 > [ 101.667117][ T8885] sys_madvise+0x1068/0x1080 > [ 101.667185][ T8885] system_call+0x5c/0x68 > > The reason is that __test_page_isolated_in_pageblock doesn't recognize > hugetlb tail pages as the HWPoison bit is not transferred from the head > page. Pfn walker then doesn't recognize those pages and so EBUSY is > returned up the call chain. > > The proper fix would be to handle HWPoison throughout the huge page but > considering there is a WIP to rework that code considerably let's go > with a simple and easily backportable workaround and simply check the > the head of a compound page for the HWPoison flag. > > Reported-and-analyzed-by: Qian Cai <cai@lca.pw> > Fixes: b023f46813cd ("memory-hotplug: skip HWPoisoned page when offlining pages") > Cc: stable > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > mm/page_isolation.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 89c19c0feadb..5fb3fee16fde 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -274,7 +274,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, > * simple way to verify that as VM_BUG_ON(), though. > */ > pfn += 1 << page_order(page); > - else if (skip_hwpoisoned_pages && PageHWPoison(page)) > + else if (skip_hwpoisoned_pages && PageHWPoison(compound_head(page))) > /* A HWPoisoned page cannot be also PageBuddy */ > pfn++; > else >
With the extended description, this makes sense to me now :)
Acked-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
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