From: Rik van Riel riel@surriel.com Subject: mm: invalidate hwpoison page cache page in fault path

Sometimes the page offlining code can leave behind a hwpoisoned clean page cache page. This can lead to programs being killed over and over and over again as they fault in the hwpoisoned page, get killed, and then get re-spawned by whatever wanted to run them.

This is particularly embarrassing when the page was offlined due to having too many corrected memory errors. Now we are killing tasks due to them trying to access memory that probably isn't even corrupted.

This problem can be avoided by invalidating the page from the page fault handler, which already has a branch for dealing with these kinds of pages. With this patch we simply pretend the page fault was successful if the page was invalidated, return to userspace, incur another page fault, read in the file from disk (to a new memory page), and then everything works again.

Link: https://lkml.kernel.org/r/20220212213740.423efcea@imladris.surriel.com Signed-off-by: Rik van Riel riel@surriel.com Reviewed-by: Miaohe Lin linmiaohe@huawei.com Acked-by: Naoya Horiguchi naoya.horiguchi@nec.com Reviewed-by: Oscar Salvador osalvador@suse.de Cc: John Hubbard jhubbard@nvidia.com Cc: Mel Gorman mgorman@suse.de Cc: Johannes Weiner hannes@cmpxchg.org Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/memory.c~mm-clean-up-hwpoison-page-cache-page-in-fault-path +++ a/mm/memory.c @@ -3877,11 +3877,16 @@ static vm_fault_t __do_fault(struct vm_f return ret;

if (unlikely(PageHWPoison(vmf->page))) { - if (ret & VM_FAULT_LOCKED) + vm_fault_t poisonret = VM_FAULT_HWPOISON; + if (ret & VM_FAULT_LOCKED) { + /* Retry if a clean page was removed from the cache. */ + if (invalidate_inode_page(vmf->page)) + poisonret = 0; unlock_page(vmf->page); + } put_page(vmf->page); vmf->page = NULL; - return VM_FAULT_HWPOISON; + return poisonret; }

if (unlikely(!(ret & VM_FAULT_LOCKED))) _