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Mon, 20 May 2024 09:51:46 +0800 Subject: Re: [PATCH v3] mm/huge_memory: don't unpoison huge_zero_folio To: Anshuman Khandual , CC: , , , , , , References: <20240516122608.22610-1-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Mon, 20 May 2024 09:51:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.135.154] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 9CABCC0005 X-Stat-Signature: 9uftyyejzmeejcp5utw4nzut5jx3oyfp X-HE-Tag: 1716169933-396739 X-HE-Meta: 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 nXhS/hXW Q6VFzDCDDFb9+SB4IRA1N+A8+WmuSR4L4XXsC15eG0gXu9yObC8ExcnRPcTAM6HHOUCIt6lg83vhREOG+oBiEuUBiVzeaiWDuZHt3XJ/vHICDpLKr6VFhH6CB4QDup1isVQsHl32+ReMpgB5MHLEDCo58sHq0YxUXVDO+nWtQiAuYl0EWJo3DKRNXUuN1wbhtGjS1/998TWfFsLh0Jszc2ZtBTB/ehG/BI9Qm2qypH56HWU0Hs1Fel0CJBChAOqKfmFWS0TSYAu6NB9MZgBvnSpRCeUncTm1RUuWozGa7CIRYfQw1Xc0jzUdkbrlFegOV9jwkzLpeZOsJ0+yzhecDdRY7rFo5ZDl+YLPtrWEtaTzYPBxI1T0gvDTvZUcddP7gvkPyv2k5H7ySxu3mbTdqnxUBErBGMbr1ukDyYOv5hORv7Jd/VQ/kVxnSqLUgWbt1rEva X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/5/17 15:02, Anshuman Khandual wrote: > On 5/16/24 17:56, Miaohe Lin wrote: >> When I did memory failure tests recently, below panic occurs: >> >> kernel BUG at include/linux/mm.h:1135! >> invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >> CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f156fe-dirty #14 >> RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0 >> RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246 >> RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8 >> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0 >> RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492 >> R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000 >> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00 >> FS: 0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0 >> Call Trace: >> >> do_shrink_slab+0x14f/0x6a0 >> shrink_slab+0xca/0x8c0 >> shrink_node+0x2d0/0x7d0 >> balance_pgdat+0x33a/0x720 >> kswapd+0x1f3/0x410 >> kthread+0xd5/0x100 >> ret_from_fork+0x2f/0x50 >> ret_from_fork_asm+0x1a/0x30 >> >> Modules linked in: mce_inject hwpoison_inject >> ---[ end trace 0000000000000000 ]--- >> RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0 >> RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246 >> RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8 >> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0 >> RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492 >> R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000 >> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00 >> FS: 0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0 >> >> The root cause is that HWPoison flag will be set for huge_zero_folio >> without increasing the folio refcnt. But then unpoison_memory() will >> decrease the folio refcnt unexpectly as it appears like a successfully > > Small nit, a typo in here ^^^^^ s/unexpectly/unexpectedly/. Thanks for finding out this typo. And thanks Andrew for fixing the typo. > >> hwpoisoned folio leading to VM_BUG_ON_PAGE(page_ref_count(page) == 0) >> when releasing huge_zero_folio. >> >> Skip unpoisoning huge_zero_folio in unpoison_memory() to fix this issue. >> We're not prepared to unpoison huge_zero_folio yet. >> >> Fixes: 478d134e9506 ("mm/huge_memory: do not overkill when splitting huge_zero_page") > > The target commit looks right. > >> Signed-off-by: Miaohe Lin >> Acked-by: David Hildenbrand >> Reviewed-by: Yang Shi >> Reviewed-by: Oscar Salvador >> Cc: >> --- >> v3: >> Move up is_huge_zero_folio() check and change return value to >> -EOPNOTSUPP per Oscar. >> Collect Reviewed-by and Acked-by tag. Thanks. >> v2: >> Change to simply check for the huge zero page per David. Thanks. >> --- >> mm/memory-failure.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index 16ada4fb02b7..a9fe9eda593f 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -2546,6 +2546,13 @@ int unpoison_memory(unsigned long pfn) >> goto unlock_mutex; >> } >> >> + if (is_huge_zero_folio(folio)) { >> + unpoison_pr_info("Unpoison: huge zero page is not supported %#lx\n", >> + pfn, &unpoison_rs); >> + ret = -EOPNOTSUPP; >> + goto unlock_mutex; >> + } >> + >> if (!PageHWPoison(p)) { >> unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n", >> pfn, &unpoison_rs); > > This patch applies on latest linux-next but not on latest mainline as > is_huge_zero_folio() is absent there. It could be simply replaced with is_huge_zero_page(). > > Reviewed-by: Anshuman Khandual Thanks. .