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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [PATCH 2/2] mm: ksm: Support hwpoison for ksm page To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: "akpm@linux-foundation.org" , "linmiaohe@huawei.com" , "wangkefeng.wang@huawei.com" , "sunnanyong@huawei.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" References: <20230330074501.205092-1-xialonglong1@huawei.com> <20230330074501.205092-3-xialonglong1@huawei.com> <20230331054243.GB1435482@hori.linux.bs1.fc.nec.co.jp> From: xialonglong In-Reply-To: <20230331054243.GB1435482@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.229] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600003.china.huawei.com (7.193.23.202) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 45BBD14001C X-Stat-Signature: tca1ir3s4n4zdqzc4tfkxgrz88wi3imz X-Rspam-User: X-HE-Tag: 1680604969-690718 X-HE-Meta: U2FsdGVkX1+RDzDkHIygU9VWQfXE4w13Lh7dzfxcZGCLnzIrfR6/d4ycNuWlW30TVbcaKI1uEw1JXL11nEyK77A22l4mPimY417gcS+j62ajYRVInDQVvbK754KhpnT5eo5VmixPDt1IIeve0ptY0/FjEg05prelr4G0uhPck0Ul9L07Slvqn/+JU5Xy/rlLMEEBgPQQfd/Vli3RkrdsrlW7V/R0ppQSW995Y9+hOQ+IxYyn2mJKBEaYE7m2/RPG7B3OUgajOFBa66ArTijvGKkI5F7Lx7HkSSg4DMCsW6qNNqR2I8ZQyT3yBsoWOhxGgfuxtc2f8gBQgquY54peTPGmpHzwNgCZGpPnyIewmG70fdztR+c+VEkeoNDw4SCBsq+NaT95mRRUxYnOSZ8zmqL85YzPa4isobDeKAvUv5dMbfVkBJjgdZZjlFGW5iX6mc9rU2Tg9XtPEO8Zn7ilHOcoMZ0OVD2WXUFe6y9rzGNUUjpxzaCWDC38L/xd2O/fSUd4vPtauNKQtJSgaUIp2ZlsNBK8hoiL47sra+6C9au0vCUKBPwezFAcP8V9tkHW6g+fKrBkJQF+hdK+4kFVFRlA9U98qkJLOaLhPX4aBSLtvoHuV9dXsZ789MuJqGAYMgcKNhnEKzgjr6yiHCY17WN+uG2qfGmyNWsrp2QnjTyAqZBG5tMtHfGPcyLTLBbfsEQZ9DynueI0ewPIU612bgdQhJvDW5qe3wm4DZBtnPszaKnZAdi67N48zq24N0GAbelJJSuJJ7uQ+GOpi/WYhmlPxcJuQLStniU+BJMCwEnsrk+cPtSycOE/fOVPK5qS5IysKGiY7F/+eBkPlASu79XzHP7iPJcVzSBMx5grjLYijRnZoQ+oKo4eewR5uhGGAsd2Jpg/tvvQRJKO79MrrGm/Cgr9kI6h1RbzsnvsSpKOsiBcOWlmvt1TZbGphZCnzLOJahO5bW3gmhwHtW0 YuaSgjzI OQlmVDggYUixmNxMQ17pfxPkf+wzvkLShAbeU5UKmE5PKSA9yHLYUEUIqRpT0Bu9FbQ0IwnNK5rUz3SHKS//lcB6D8O7Bmj6RX0h6ZEBHPFVFdXOCaRMZX3TjfPr6TAK1ochDip5G4lgBAnryOfeYVmzfzZIFIuM0fCHfCMyfnV5IxBfq+HkaTDBw/gn9VqOveqgU2BZ8e5mu/JM88D7/5mTT+g== 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: Thank you very much for your reply. Your suggestion is indeed very helpful and I will take some time to consider how to implement it. Once I have a clear plan, I will send a separate patch to make it happen. Best regards, Longlong Xia 在 2023/3/31 13:42, HORIGUCHI NAOYA(堀口 直也) 写道: > On Thu, Mar 30, 2023 at 03:45:01PM +0800, Longlong Xia wrote: >> hwpoison_user_mappings() is updated to support ksm pages, and add >> collect_procs_ksm() to collect processes when the error hit an ksm >> page. The difference from collect_procs_anon() is that it also needs >> to traverse the rmap-item list on the stable node of the ksm page. >> At the same time, add_to_kill_ksm() is added to handle ksm pages. And >> task_in_to_kill_list() is added to avoid duplicate addition of tsk to >> the to_kill list. This is because when scanning the list, if the pages >> that make up the ksm page all come from the same process, they may be >> added repeatedly. >> >> Signed-off-by: Longlong Xia > > I don't find any specific issue by code review for now, so I'll try to > test your patches. > > I have one comment about duplicated KSM pages. It seems that KSM controls > page duplication by limiting deduplication factor with max_page_sharing, > primarily for performance reason. But I think it's imporant from memory > RAS's viewpoint too because that means we could allow recovery from memory > errors on a KSM page by making affected processes to switch to the duplicated > pages (without killing the processes!). Maybe this might be beyond the scope > of this patchset and I'm not sure how hard it is, but if you are interested > in this issue, that's really nice. > > Thanks, > Naoya Horiguchi