Messages in this thread | | | Date | Mon, 10 Aug 2020 11:22:55 -0400 | From | Qian Cai <> | Subject | Re: [PATCH v6 00/12] HWPOISON: soft offline rework |
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On Thu, Aug 06, 2020 at 06:49:11PM +0000, nao.horiguchi@gmail.com wrote: > Hi, > > This patchset is the latest version of soft offline rework patchset > targetted for v5.9. > > Since v5, I dropped some patches which tweak refcount handling in > madvise_inject_error() to avoid the "unknown refcount page" error. > I don't confirm the fix (that didn't reproduce with v5 in my environment), > but this change surely call soft_offline_page() after holding refcount, > so the error should not happen any more.
With this patchset, arm64 is still suffering from premature 512M-size hugepages allocation failures.
# git clone https://gitlab.com/cailca/linux-mm # cd linux-mm; make # ./random 1 - start: migrate_huge_offline - use NUMA nodes 0,1. - mmap and free 2147483648 bytes hugepages on node 0 - mmap and free 2147483648 bytes hugepages on node 1 madvise: Cannot allocate memory
[ 292.456538][ T3685] soft offline: 0x8a000: hugepage isolation failed: 0, page count 2, type 7ffff80001000e (referenced|uptodate|dirty|head) [ 292.469113][ T3685] Soft offlining pfn 0x8c000 at process virtual address 0xffff60000000 [ 292.983855][ T3685] Soft offlining pfn 0x88000 at process virtual address 0xffff40000000 [ 293.271369][ T3685] Soft offlining pfn 0x8a000 at process virtual address 0xffff60000000 [ 293.834030][ T3685] Soft offlining pfn 0xa000 at process virtual address 0xffff40000000 [ 293.851378][ T3685] soft offline: 0xa000: hugepage migration failed -12, type 7ffff80001000e (referenced|uptodate|dirty|head)
The fresh-booted system still had 40G+ memory free before running the test.
Reverting the following commits allowed the test to run succesfully over and over again.
"mm, hwpoison: remove recalculating hpage" "mm,hwpoison-inject: don't pin for hwpoison_filter" "mm,hwpoison: Un-export get_hwpoison_page and make it static" "mm,hwpoison: kill put_hwpoison_page" "mm,hwpoison: unify THP handling for hard and soft offline" "mm,hwpoison: rework soft offline for free pages" "mm,hwpoison: rework soft offline for in-use pages" "mm,hwpoison: refactor soft_offline_huge_page and __soft_offline_page"
i.e., it is not enough to only revert,
mm,hwpoison: double-check page count in __get_any_page() mm,hwpoison: introduce MF_MSG_UNSPLIT_THP mm,hwpoison: return 0 if the page is already poisoned in soft-offline
> > Dropped patches > - mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED > - mm,madvise: Refactor madvise_inject_error > - mm,hwpoison: remove MF_COUNT_INCREASED > - mm,hwpoison: remove flag argument from soft offline functions > > Thanks, > Naoya Horiguchi > > Quoting cover letter of v5: > ---- > 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. > > --- > Previous versions: > v1: https://lore.kernel.org/linux-mm/1541746035-13408-1-git-send-email-n-horiguchi@ah.jp.nec.com/ > v2: https://lore.kernel.org/linux-mm/20191017142123.24245-1-osalvador@suse.de/ > v3: https://lore.kernel.org/linux-mm/20200624150137.7052-1-nao.horiguchi@gmail.com/ > v4: https://lore.kernel.org/linux-mm/20200716123810.25292-1-osalvador@suse.de/ > v5: https://lore.kernel.org/linux-mm/20200805204354.GA16406@hori.linux.bs1.fc.nec.co.jp/T/#t > --- > Summary: > > Naoya Horiguchi (5): > mm,hwpoison: cleanup unused PageHuge() check > mm, hwpoison: remove recalculating hpage > mm,hwpoison-inject: don't pin for hwpoison_filter > mm,hwpoison: introduce MF_MSG_UNSPLIT_THP > mm,hwpoison: double-check page count in __get_any_page() > > Oscar Salvador (7): > mm,hwpoison: Un-export get_hwpoison_page and make it static > mm,hwpoison: Kill put_hwpoison_page > mm,hwpoison: Unify THP handling for hard and soft offline > mm,hwpoison: Rework soft offline for free pages > mm,hwpoison: Rework soft offline for in-use pages > mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page > mm,hwpoison: Return 0 if the page is already poisoned in soft-offline > > include/linux/mm.h | 3 +- > include/linux/page-flags.h | 6 +- > include/ras/ras_event.h | 3 + > mm/hwpoison-inject.c | 18 +-- > mm/madvise.c | 5 - > mm/memory-failure.c | 307 +++++++++++++++++++++------------------------ > mm/migrate.c | 11 +- > mm/page_alloc.c | 60 +++++++-- > 8 files changed, 203 insertions(+), 210 deletions(-)
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