The patch titled Subject: mm/memory-failure: fix handling of dissolved but not taken off from buddy pages has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-memory-failure-fix-handling-of-dissolved-but-not-taken-off-from-buddy-pages.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Miaohe Lin linmiaohe@huawei.com Subject: mm/memory-failure: fix handling of dissolved but not taken off from buddy pages Date: Thu, 23 May 2024 15:12:17 +0800

When I did memory failure tests recently, below panic occurs:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00 flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff) raw: 06fffe0000000000 dead000000000100 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000009 00000000ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(!PageBuddy(page)) ------------[ cut here ]------------ kernel BUG at include/linux/page-flags.h:1009! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:__del_page_from_free_list+0x151/0x180 RSP: 0018:ffffa49c90437998 EFLAGS: 00000046 RAX: 0000000000000035 RBX: 0000000000000009 RCX: ffff8dd8dfd1c9c8 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff8dd8dfd1c9c0 RBP: ffffd901233b8000 R08: ffffffffab5511f8 R09: 0000000000008c69 R10: 0000000000003c15 R11: ffffffffab5511f8 R12: ffff8dd8fffc0c80 R13: 0000000000000001 R14: ffff8dd8fffc0c80 R15: 0000000000000009 FS: 00007ff916304740(0000) GS:ffff8dd8dfd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055eae50124c8 CR3: 00000008479e0000 CR4: 00000000000006f0 Call Trace: <TASK> __rmqueue_pcplist+0x23b/0x520 get_page_from_freelist+0x26b/0xe40 __alloc_pages_noprof+0x113/0x1120 __folio_alloc_noprof+0x11/0xb0 alloc_buddy_hugetlb_folio.isra.0+0x5a/0x130 __alloc_fresh_hugetlb_folio+0xe7/0x140 alloc_pool_huge_folio+0x68/0x100 set_max_huge_pages+0x13d/0x340 hugetlb_sysctl_handler_common+0xe8/0x110 proc_sys_call_handler+0x194/0x280 vfs_write+0x387/0x550 ksys_write+0x64/0xe0 do_syscall_64+0xc2/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff916114887 RSP: 002b:00007ffec8a2fd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000055eae500e350 RCX: 00007ff916114887 RDX: 0000000000000004 RSI: 000055eae500e390 RDI: 0000000000000003 RBP: 000055eae50104c0 R08: 0000000000000000 R09: 000055eae50104c0 R10: 0000000000000077 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000004 R14: 00007ff916216b80 R15: 00007ff916216a00 </TASK> Modules linked in: mce_inject hwpoison_inject ---[ end trace 0000000000000000 ]---

And before the panic, there had an warning about bad page state:

BUG: Bad page state in process page-types pfn:8cee00 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00 flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff) page_type: 0xffffff7f(buddy) raw: 06fffe0000000000 ffffd901241c0008 ffffd901240f8008 0000000000000000 raw: 0000000000000000 0000000000000009 00000000ffffff7f 0000000000000000 page dumped because: nonzero mapcount Modules linked in: mce_inject hwpoison_inject CPU: 8 PID: 154211 Comm: page-types Not tainted 6.9.0-rc4-00499-g5544ec3178e2-dirty #22 Call Trace: <TASK> dump_stack_lvl+0x83/0xa0 bad_page+0x63/0xf0 free_unref_page+0x36e/0x5c0 unpoison_memory+0x50b/0x630 simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110 debugfs_attr_write+0x42/0x60 full_proxy_write+0x5b/0x80 vfs_write+0xcd/0x550 ksys_write+0x64/0xe0 do_syscall_64+0xc2/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f189a514887 RSP: 002b:00007ffdcd899718 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f189a514887 RDX: 0000000000000009 RSI: 00007ffdcd899730 RDI: 0000000000000003 RBP: 00007ffdcd8997a0 R08: 0000000000000000 R09: 00007ffdcd8994b2 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdcda199a8 R13: 0000000000404af1 R14: 000000000040ad78 R15: 00007f189a7a5040 </TASK>

The root cause should be the below race:

memory_failure try_memory_failure_hugetlb me_huge_page __page_handle_poison dissolve_free_hugetlb_folio drain_all_pages -- Buddy page can be isolated e.g. for compaction. take_page_off_buddy -- Failed as page is not in the buddy list. -- Page can be putback into buddy after compaction. page_ref_inc -- Leads to buddy page with refcnt = 1.

Then unpoison_memory() can unpoison the page and send the buddy page back into buddy list again leading to the above bad page state warning. And bad_page() will call page_mapcount_reset() to remove PageBuddy from buddy page leading to later VM_BUG_ON_PAGE(!PageBuddy(page)) when trying to allocate this page.

Fix this issue by only treating __page_handle_poison() as successful when it returns 1.

Link: https://lkml.kernel.org/r/20240523071217.1696196-1-linmiaohe@huawei.com Fixes: ceaf8fbea79a ("mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage") Signed-off-by: Miaohe Lin linmiaohe@huawei.com Cc: Naoya Horiguchi nao.horiguchi@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory-failure.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fix-handling-of-dissolved-but-not-taken-off-from-buddy-pages +++ a/mm/memory-failure.c @@ -1221,7 +1221,7 @@ static int me_huge_page(struct page_stat * subpages. */ folio_put(folio); - if (__page_handle_poison(p) >= 0) { + if (__page_handle_poison(p) > 0) { page_ref_inc(p); res = MF_RECOVERED; } else { @@ -2091,7 +2091,7 @@ retry: */ if (res == 0) { folio_unlock(folio); - if (__page_handle_poison(p) >= 0) { + if (__page_handle_poison(p) > 0) { page_ref_inc(p); res = MF_RECOVERED; } else { _

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-huge_memory-dont-unpoison-huge_zero_folio.patch mm-memory-failure-fix-handling-of-dissolved-but-not-taken-off-from-buddy-pages.patch