From: Rik van Riel riel@surriel.com Subject: mm,hwpoison: unmap poisoned page before invalidation
In some cases it appears the invalidation of a hwpoisoned page fails because the page is still mapped in another process. This can cause a program to be continuously restarted and die when it page faults on the page that was not invalidated. Avoid that problem by unmapping the hwpoisoned page when we find it.
Another issue is that sometimes we end up oopsing in finish_fault, if the code tries to do something with the now-NULL vmf->page. I did not hit this error when submitting the previous patch because there are several opportunities for alloc_set_pte to bail out before accessing vmf->page, and that apparently happened on those systems, and most of the time on other systems, too.
However, across several million systems that error does occur a handful of times a day. It can be avoided by returning VM_FAULT_NOPAGE which will cause do_read_fault to return before calling finish_fault.
Link: https://lkml.kernel.org/r/20220325161428.5068d97e@imladris.surriel.com Fixes: e53ac7374e64 ("mm: invalidate hwpoison page cache page in fault path") Signed-off-by: Rik van Riel riel@surriel.com Reviewed-by: Miaohe Lin linmiaohe@huawei.com Tested-by: Naoya Horiguchi naoya.horiguchi@nec.com Reviewed-by: Oscar Salvador osalvador@suse.de Cc: Mel Gorman mgorman@suse.de Cc: Johannes Weiner hannes@cmpxchg.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/memory.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/mm/memory.c~mmhwpoison-unmap-poisoned-page-before-invalidation +++ a/mm/memory.c @@ -3918,14 +3918,18 @@ static vm_fault_t __do_fault(struct vm_f return ret;
if (unlikely(PageHWPoison(vmf->page))) { + struct page *page = vmf->page; vm_fault_t poisonret = VM_FAULT_HWPOISON; if (ret & VM_FAULT_LOCKED) { + if (page_mapped(page)) + unmap_mapping_pages(page_mapping(page), + page->index, 1, false); /* Retry if a clean page was removed from the cache. */ - if (invalidate_inode_page(vmf->page)) - poisonret = 0; - unlock_page(vmf->page); + if (invalidate_inode_page(page)) + poisonret = VM_FAULT_NOPAGE; + unlock_page(page); } - put_page(vmf->page); + put_page(page); vmf->page = NULL; return poisonret; } _