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Tue, 10 Sep 2024 10:19:47 +0800 Subject: Re: [PATCH 2/2] mm: support poison recovery from copy_present_page() To: Kefeng Wang , 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> From: Miaohe Lin Message-ID: <635585c1-5d51-6a23-70ad-560e164068f6@huawei.com> Date: Tue, 10 Sep 2024 10:19:46 +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: <20240906024201.1214712-3-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.127.72] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemd200019.china.huawei.com (7.221.188.193) X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AEC6BC0003 X-Stat-Signature: xzhoqbgh4uaztap3wuicpr5p1cwun5ox X-Rspam-User: X-HE-Tag: 1725934791-5680 X-HE-Meta: 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 gB4aTfg1 FevA4OU9WJqLIqZGvXb9wFPR0iRV+w18DaO0a65hzU1fXN2FT+hxWUkKjnvkRkcZ4Utb+uA4I4cJ0Rrb6GUUiXZarmQ/EIXv0j7OW9WPhzJQCEozKK/jwnfzWGpqAex8CsOIxE9/s3N2jr706P/RbbuieBkkLIGDDxCDKrgTUvVgv5EKB7fsDoSc2Sl04+ibXyiua9/GQdqzbnwRyhWerQADycVK3bHLPAa4k7MU6hBAUbYJpRSXiq3GSPjOXq2Q8p3suZZZVMrUNicLo98GklQnofg== 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 2024/9/6 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. > 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. Thanks. .