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Message-ID: <783bfb90-c298-410c-893c-d497a1a2727f@huawei.com>
Date: Wed, 19 Feb 2025 11:34:12 +0800
From: mawupeng <mawupeng1@...wei.com>
To: <linmiaohe@...wei.com>
CC: <mawupeng1@...wei.com>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>, <akpm@...ux-foundation.org>,
<david@...hat.com>, <osalvador@...e.de>, <nao.horiguchi@...il.com>,
<mhocko@...e.com>
Subject: Re: [PATCH v3 1/3] mm: memory-failure: update ttu flag inside
unmap_poisoned_folio
On 2025/2/19 10:50, Miaohe Lin wrote:
> On 2025/2/17 9:43, Wupeng Ma wrote:
>> From: Ma Wupeng <mawupeng1@...wei.com>
>>
>> Commit 6da6b1d4a7df ("mm/hwpoison: convert TTU_IGNORE_HWPOISON to
>> TTU_HWPOISON") introduce TTU_HWPOISON to replace TTU_IGNORE_HWPOISON
>> in order to stop send SIGBUS signal when accessing an error page after
>> a memory error on a clean folio. However during page migration, anon
>> folio must be set with TTU_HWPOISON during unmap_*(). For pagecache
>> we need some policy just like the one in hwpoison_user_mappings to
>> set this flag. So move this policy from hwpoison_user_mappings to
>> unmap_poisoned_folio to handle this warning properly.
>>
>> Warning will be produced during unamp poison folio with the following log:
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 1 PID: 365 at mm/rmap.c:1847 try_to_unmap_one+0x8fc/0xd3c
>> Modules linked in:
>> CPU: 1 UID: 0 PID: 365 Comm: bash Tainted: G W 6.13.0-rc1-00018-gacdb4bbda7ab #42
>> Tainted: [W]=WARN
>> Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
>> pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> pc : try_to_unmap_one+0x8fc/0xd3c
>> lr : try_to_unmap_one+0x3dc/0xd3c
>> Call trace:
>> try_to_unmap_one+0x8fc/0xd3c (P)
>> try_to_unmap_one+0x3dc/0xd3c (L)
>> rmap_walk_anon+0xdc/0x1f8
>> rmap_walk+0x3c/0x58
>> try_to_unmap+0x88/0x90
>> unmap_poisoned_folio+0x30/0xa8
>> do_migrate_range+0x4a0/0x568
>> offline_pages+0x5a4/0x670
>> memory_block_action+0x17c/0x374
>> memory_subsys_offline+0x3c/0x78
>> device_offline+0xa4/0xd0
>> state_store+0x8c/0xf0
>> dev_attr_store+0x18/0x2c
>> sysfs_kf_write+0x44/0x54
>> kernfs_fop_write_iter+0x118/0x1a8
>> vfs_write+0x3a8/0x4bc
>> ksys_write+0x6c/0xf8
>> __arm64_sys_write+0x1c/0x28
>> invoke_syscall+0x44/0x100
>> el0_svc_common.constprop.0+0x40/0xe0
>> do_el0_svc+0x1c/0x28
>> el0_svc+0x30/0xd0
>> el0t_64_sync_handler+0xc8/0xcc
>> el0t_64_sync+0x198/0x19c
>> ---[ end trace 0000000000000000 ]---
>>
>> Fixes: 6da6b1d4a7df ("mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON")
>> Suggested-by: David Hildenbrand <david@...hat.com>
>> Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>
>> Acked-by: David Hildenbrand <david@...hat.com>
>
> Thanks. LGTM. One nit below.
>
> Acked-by: Miaohe Lin <linmiaohe@...wei.com>
>
>> ---
>> mm/internal.h | 5 ++--
>> mm/memory-failure.c | 61 +++++++++++++++++++++++----------------------
>> mm/memory_hotplug.c | 3 ++-
>> 3 files changed, 36 insertions(+), 33 deletions(-)
>>
>> diff --git a/mm/internal.h b/mm/internal.h
>> index 9826f7dce607..c9186ca8d7c2 100644
>> --- a/mm/internal.h
>> +++ b/mm/internal.h
>> @@ -1102,7 +1102,7 @@ static inline int find_next_best_node(int node, nodemask_t *used_node_mask)
>> * mm/memory-failure.c
>> */
>> #ifdef CONFIG_MEMORY_FAILURE
>> -void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu);
>> +int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill);
>> void shake_folio(struct folio *folio);
>> extern int hwpoison_filter(struct page *p);
>>
>> @@ -1125,8 +1125,9 @@ unsigned long page_mapped_in_vma(const struct page *page,
>> struct vm_area_struct *vma);
>>
>> #else
>> -static inline void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
>> +static inline int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill)
>> {
>> + return -EBUSY;
>> }
>> #endif
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index a7b8ccd29b6f..b5212b6e330a 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1556,8 +1556,34 @@ static int get_hwpoison_page(struct page *p, unsigned long flags)
>> return ret;
>> }
>>
>> -void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
>> +int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill)
>> {
>> + enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC | TTU_HWPOISON;
>> + struct address_space *mapping;
>> +
>> + if (folio_test_swapcache(folio)) {
>> + pr_err("%#lx: keeping poisoned page in swap cache\n", pfn);
>> + ttu &= ~TTU_HWPOISON;
>> + }
>> +
>> + /*
>> + * Propagate the dirty bit from PTEs to struct page first, because we
>> + * need this to decide if we should kill or just drop the page.
>> + * XXX: the dirty test could be racy: set_page_dirty() may not always
>> + * be called inside page lock (it's recommended but not enforced).
>> + */
>> + mapping = folio_mapping(folio);
>> + if (!must_kill && !folio_test_dirty(folio) && mapping &&
>> + mapping_can_writeback(mapping)) {
>> + if (folio_mkclean(folio)) {
>> + folio_set_dirty(folio);
>> + } else {
>> + ttu &= ~TTU_HWPOISON;
>> + pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
>> + pfn);
>> + }
>> + }
>> +
>> if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {
>> struct address_space *mapping;
>
> This mapping can be removed as we have already defined one above. But this is trivial.
Thanks.
I will resend this patch with the duplicate defination removed.
>
> Thanks.
> .
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