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Date: Tue, 26 Oct 2021 18:04:13 -0700 From: Yang Shi <shy828301@...il.com> To: Naoya Horiguchi <naoya.horiguchi@...ux.dev> Cc: Linux MM <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, David Hildenbrand <david@...hat.com>, Oscar Salvador <osalvador@...e.de>, Michal Hocko <mhocko@...e.com>, Ding Hui <dinghui@...gfor.com.cn>, Tony Luck <tony.luck@...el.com>, "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>, Miaohe Lin <linmiaohe@...wei.com>, Peter Xu <peterx@...hat.com>, Naoya Horiguchi <naoya.horiguchi@....com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2 2/4] mm/hwpoison: remove race consideration On Mon, Oct 25, 2021 at 4:06 PM Naoya Horiguchi <naoya.horiguchi@...ux.dev> wrote: > > From: Naoya Horiguchi <naoya.horiguchi@....com> > > Now memory_failure() and unpoison_memory() are protected by mf_mutex, > so no need to explicitly check races between them. So remove them. It seems this patch could be folded into patch #1. Some "unlock_mutex" were added by patch #1 then they were removed by this patch immediately, it seems a bit of a waste and this patch is actually the by-product of patch #1. > > Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com> > --- > mm/memory-failure.c | 37 ------------------------------------- > 1 file changed, 37 deletions(-) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 97297edfbd8e..a47b741ca04b 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1507,14 +1507,6 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) > lock_page(head); > page_flags = head->flags; > > - if (!PageHWPoison(head)) { > - pr_err("Memory failure: %#lx: just unpoisoned\n", pfn); > - num_poisoned_pages_dec(); > - unlock_page(head); > - put_page(head); > - return 0; > - } > - > /* > * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so > * simply disable it. In order to make it work properly, we need > @@ -1789,16 +1781,6 @@ int memory_failure(unsigned long pfn, int flags) > */ > page_flags = p->flags; > > - /* > - * unpoison always clear PG_hwpoison inside page lock > - */ > - if (!PageHWPoison(p)) { > - pr_err("Memory failure: %#lx: just unpoisoned\n", pfn); > - num_poisoned_pages_dec(); > - unlock_page(p); > - put_page(p); > - goto unlock_mutex; > - } > if (hwpoison_filter(p)) { > if (TestClearPageHWPoison(p)) > num_poisoned_pages_dec(); > @@ -2016,17 +1998,6 @@ int unpoison_memory(unsigned long pfn) > goto unlock_mutex; > } > > - /* > - * unpoison_memory() can encounter thp only when the thp is being > - * worked by memory_failure() and the page lock is not held yet. > - * In such case, we yield to memory_failure() and make unpoison fail. > - */ > - if (!PageHuge(page) && PageTransHuge(page)) { > - unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n", > - pfn, &unpoison_rs); > - goto unlock_mutex; > - } > - > if (!get_hwpoison_page(p, flags)) { > if (TestClearPageHWPoison(p)) > num_poisoned_pages_dec(); > @@ -2035,20 +2006,12 @@ int unpoison_memory(unsigned long pfn) > goto unlock_mutex; > } > > - lock_page(page); > - /* > - * This test is racy because PG_hwpoison is set outside of page lock. > - * That's acceptable because that won't trigger kernel panic. Instead, > - * the PG_hwpoison page will be caught and isolated on the entrance to > - * the free buddy page pool. > - */ > if (TestClearPageHWPoison(page)) { > unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n", > pfn, &unpoison_rs); > num_poisoned_pages_dec(); > freeit = 1; > } > - unlock_page(page); > > put_page(page); > if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) > -- > 2.25.1 >
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