From 65d3440e8d2e9e024ef2357f8ff021611b068c99 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 26 Aug 2022 10:18:07 -0700 Subject: mm/memory-failure: fix detection of memory_failure() handlers Some pagemap types, like MEMORY_DEVICE_GENERIC (device-dax) do not even have pagemap ops which results in crash signatures like this: BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8000000205073067 P4D 8000000205073067 PUD 2062b3067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 22 PID: 4535 Comm: device-dax Tainted: G OE N 6.0.0-rc2+ #59 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:memory_failure+0x667/0xba0 [..] Call Trace: ? _printk+0x58/0x73 do_madvise.part.0.cold+0xaf/0xc5 Check for ops before checking if the ops have a memory_failure() handler. Link: https://lkml.kernel.org/r/166153428781.2758201.1990616683438224741.stgit@dwillia2-xfh.jf.intel.com Fixes: 33a8f7f2b3a3 ("pagemap,pmem: introduce ->memory_failure()") Signed-off-by: Dan Williams Acked-by: Naoya Horiguchi Reviewed-by: Miaohe Lin Reviewed-by: Christoph Hellwig Cc: Shiyang Ruan Cc: Darrick J. Wong Cc: Al Viro Cc: Dave Chinner Cc: Goldwyn Rodrigues Cc: Jane Chu Cc: Matthew Wilcox Cc: Ritesh Harjani Signed-off-by: Andrew Morton --- mm/memory-failure.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 14439806b5ef..8a4294afbfa0 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1928,7 +1928,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, * Call driver's implementation to handle the memory failure, otherwise * fall back to generic handler. */ - if (pgmap->ops->memory_failure) { + if (pgmap_has_memory_failure(pgmap)) { rc = pgmap->ops->memory_failure(pgmap, pfn, 1, flags); /* * Fall back to generic handler too if operation is not -- cgit v1.2.3