Messages in this thread Patch in this message | | | From | Oscar Salvador <> | Subject | [PATCH v4 03/15] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED | Date | Thu, 16 Jul 2020 14:37:57 +0200 |
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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
The call to get_user_pages_fast is only to get the pointer to a struct page of a given address, pinning it is memory-poisoning handler's job, so drop the refcount grabbed by get_user_pages_fast
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Oscar Salvador <osalvador@suse.com> --- mm/madvise.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c index a16dba21cdf6..1fe89a5b8d33 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -910,16 +910,24 @@ static int madvise_inject_error(int behavior, */ size = page_size(compound_head(page)); - if (PageHWPoison(page)) { - put_page(page); + /* + * The get_user_pages_fast() is just to get the pfn of the + * given address, and the refcount has nothing to do with + * what we try to test, so it should be released immediately. + * This is racy but it's intended because the real hardware + * errors could happen at any moment and memory error handlers + * must properly handle the race. + */ + put_page(page); + + if (PageHWPoison(page)) continue; - } if (behavior == MADV_SOFT_OFFLINE) { pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n", pfn, start); - ret = soft_offline_page(pfn, MF_COUNT_INCREASED); + ret = soft_offline_page(pfn, 0); if (ret) return ret; continue; @@ -927,14 +935,6 @@ static int madvise_inject_error(int behavior, pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n", pfn, start); - - /* - * Drop the page reference taken by get_user_pages_fast(). In - * the absence of MF_COUNT_INCREASED the memory_failure() - * routine is responsible for pinning the page to prevent it - * from being released back to the page allocator. - */ - put_page(page); ret = memory_failure(pfn, 0); if (ret) return ret; -- 2.26.2
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