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Tue, 10 Sep 2024 14:35:18 +0800 Message-ID: <7318807d-ee77-48e3-a827-39cbb44b3506@huawei.com> Date: Tue, 10 Sep 2024 14:35:18 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm: support poison recovery from copy_present_page() Content-Language: en-US To: Miaohe Lin , Andrew Morton CC: , Jane Chu , Naoya Horiguchi , Tony Luck , Jiaqi Yan , David Hildenbrand References: <20240906024201.1214712-1-wangkefeng.wang@huawei.com> <20240906024201.1214712-3-wangkefeng.wang@huawei.com> <635585c1-5d51-6a23-70ad-560e164068f6@huawei.com> From: Kefeng Wang In-Reply-To: <635585c1-5d51-6a23-70ad-560e164068f6@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemf100008.china.huawei.com (7.185.36.138) X-Stat-Signature: i7mo3gtkyt5noehze5j3sxfei3q7do1u X-Rspamd-Queue-Id: 1159EC000C X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1725950123-929359 X-HE-Meta: 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 mVzr6clm yjro6/ma7rU1d5EWl3tsN2dLzn0fkvaaKd28vHzqnmGwY8NjOp7a6S6Te4xgGBZ4ZARRW/qsEk2WI/Ws8s84FrncrsLf0dOpWKj5yIf/Cm4XJEPAPoT/pjWlRtfyAbEm05Im51tzjlxSSwqALsHtp2oM+ROr69KvdO+fMvktXuEgghMOpi7zWnDOsIy7mnPtE0ksMWq7T2FLRzSvuK98zPEYpWEPTzGpiPmRrzy8keFUOCMNKrkTPyAJV11VLVy9rJ4V5AiyFwmbGSNTjhV4w+RnknA1Dt1pdVnafxm5RowAh0z2Ym7oHhuAHZA== 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 2024/9/10 10:19, Miaohe Lin wrote: > On 2024/9/6 10:42, Kefeng Wang wrote: >> Similar to other poison recovery, use copy_mc_user_highpage() to >> avoid potentially kernel panic during copy page in copy_present_page() >> from fork, once copy failed due to hwpoison in source page, we need >> to break out of copy in copy_pte_range() and release prealloc folio, >> so copy_mc_user_highpage() is moved ahead before set *prealloc to NULL. >> >> Signed-off-by: Kefeng Wang >> --- >> mm/memory.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index d310c073a1b3..6e7b78e49d1a 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -926,8 +926,11 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma >> * We have a prealloc page, all good! Take it >> * over and copy the page & arm it. >> */ >> + >> + if (copy_mc_user_highpage(&new_folio->page, page, addr, src_vma)) >> + return -EHWPOISON; >> + >> *prealloc = NULL; >> - copy_user_highpage(&new_folio->page, page, addr, src_vma); >> __folio_mark_uptodate(new_folio); >> folio_add_new_anon_rmap(new_folio, dst_vma, addr, RMAP_EXCLUSIVE); >> folio_add_lru_vma(new_folio, dst_vma); >> @@ -1166,8 +1169,9 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, >> /* >> * If we need a pre-allocated page for this pte, drop the >> * locks, allocate, and try again. >> + * If copy failed due to hwpoison in source page, break out. >> */ >> - if (unlikely(ret == -EAGAIN)) >> + if (unlikely(ret == -EAGAIN || ret == -EHWPOISON)) > > Will it be better to put checking ret against -EHWPOISON in a new line? -EAGAIN case will enter the > loop again but -EHWPOISON case never does. Maybe not a newline since we will recheck the ret in the below and return directly from copy_present_page(). > >> break; >> if (unlikely(prealloc)) { >> /* >> @@ -1197,7 +1201,7 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, >> goto out; >> } >> entry.val = 0; >> - } else if (ret == -EBUSY) { >> + } else if (ret == -EBUSY || unlikely(ret == -EHWPOISON)) { > > The caller of copy_pte_range() always set errno to -ENOMEM. So fork will failed with ENOMEM even if the real > cause is failed to copy due to hwpoison in source page. It's a pity. Yes, it's not just the new -EHWPOISON, all other errnos(ENOENT/EIO) will be ignored and return -ENOMEM instead. > > Thanks. > .