Commit 5a2ffca3 authored Oct 15, 2020 by Oscar Salvador Committed by Linus Torvalds Oct 16, 2020

mm,hwpoison: return 0 if the page is already poisoned in soft-offline



Currently, there is an inconsistency when calling soft-offline from
different paths on a page that is already poisoned.

1) madvise:

        madvise_inject_error skips any poisoned page and continues
        the loop.
        If that was the only page to madvise, it returns 0.

2) /sys/devices/system/memory/:

        When calling soft_offline_page_store()->soft_offline_page(),
        we return -EBUSY in case the page is already poisoned.
        This is inconsistent with a) the above example and b)
        memory_failure, where we return 0 if the page was poisoned.

Fix this by dropping the PageHWPoison() check in madvise_inject_error, and
let soft_offline_page return 0 if it finds the page already poisoned.

Please, note that this represents a user-api change, since now the return
error when calling soft_offline_page_store()->soft_offline_page() will be
different.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Aristeu Rozanski <aris@ruivo.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Yakunin <zeil@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200922135650.1634-12-osalvador@suse.de


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 6b9a217e

mm/madvise.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -896,11 +896,6 @@ static int madvise_inject_error(int behavior,
		*/
		size = page_size(compound_head(page));

		if (PageHWPoison(page)) {
		put_page(page);
		continue;
		}

		if (behavior == MADV_SOFT_OFFLINE) {
		pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
		pfn, start);

mm/memory-failure.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1802,7 +1802,7 @@ static int __soft_offline_page(struct page *page)
		unlock_page(page);
		put_page(page);
		pr_info("soft offline: %#lx page already poisoned\n", pfn);
		return -EBUSY;
		return 0;
		}

		if (!PageHuge(page))
		@@ -1906,7 +1906,7 @@ int soft_offline_page(unsigned long pfn, int flags)
		pr_info("soft offline: %#lx page already poisoned\n", pfn);
		if (flags & MF_COUNT_INCREASED)
		put_page(page);
		return -EBUSY;
		return 0;
		}

		get_online_mems();

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