[111/227] mm: invalidate hwpoison page cache page in fault path

Commit Message

Andrew Morton March 22, 2022, 9:44 p.m. UTC

From: Rik van Riel <[e-mail]>
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/[e-mail]
Signed-off-by: Rik van Riel <[e-mail]>
Reviewed-by: Miaohe Lin <[e-mail]>
Acked-by: Naoya Horiguchi <[e-mail]>
Reviewed-by: Oscar Salvador <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

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

Patch

--- 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)))