On Thu, Jan 18, 2018 at 02:18:20PM -0800, Laura Abbott wrote: > Fedora has been seeing similar reports > https://bugzilla.redhat.com/show_bug.cgi?id=1531779 > > Multiple reporters, one in XEN, another on actual hardware Can you chuck this patch into Fedora? Should make it easier to see if it's a "stuck bit" kind of a problem. --- From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Subject: Detect bad swap entries in lookup If we have a stuck bit in a PTE, we can end up looking for an entry in a NULL mapping, which oopses fairly quickly. Print a warning to help us debug, and return NULL which will help the machine survive a little longer. Although if it has a permanently stuck bit in a PTE, there's only a 50% chance it'll surive the insertion of a real PTE into that entry. Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> diff --git a/mm/swap_state.c b/mm/swap_state.c index 39ae7cfad90f..5a928e0191a1 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -334,8 +334,12 @@ struct page *lookup_swap_cache(swp_entry_t entry, struct vm_area_struct *vma, struct page *page; unsigned long ra_info; int win, hits, readahead; + struct address_space *swapper_space = swap_address_space(entry); + + if (WARN(!swapper_space, "Bad swp_entry: %lx\n", entry.val)) + return NULL; - page = find_get_page(swap_address_space(entry), swp_offset(entry)); + page = find_get_page(swapper_space, swp_offset(entry)); INC_CACHE_INFO(find_total); if (page) { -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
