+ mm-memory-failure-fall-back-to-vma_address-when-notify_failure-fails.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/memory-failure: fall back to vma_address() when ->notify_failure() fails
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-memory-failure-fall-back-to-vma_address-when-notify_failure-fails.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-fall-back-to-vma_address-when-notify_failure-fails.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Dan Williams <dan.j.williams@intel.com>
Subject: mm/memory-failure: fall back to vma_address() when ->notify_failure() fails
Date: Fri, 26 Aug 2022 10:18:14 -0700

In the case where a filesystem is polled to take over the memory failure
and receives -EOPNOTSUPP it indicates that page->index and page->mapping
are valid for reverse mapping the failure address.  Introduce
FSDAX_INVALID_PGOFF to distinguish when add_to_kill() is being called from
mf_dax_kill_procs() by a filesytem vs the typical memory_failure() path.

Otherwise, vma_pgoff_address() is called with an invalid fsdax_pgoff which
then trips this failing signature:

 kernel BUG at mm/memory-failure.c:319!
 invalid opcode: 0000 [#1] PREEMPT SMP PTI
 CPU: 13 PID: 1262 Comm: dax-pmd Tainted: G           OE    N 6.0.0-rc2+ #62
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 RIP: 0010:add_to_kill.cold+0x19d/0x209
 [..]
 Call Trace:
  <TASK>
  collect_procs.part.0+0x2c4/0x460
  memory_failure+0x71b/0xba0
  ? _printk+0x58/0x73
  do_madvise.part.0.cold+0xaf/0xc5

Link: https://lkml.kernel.org/r/166153429427.2758201.14605968329933175594.stgit@dwillia2-xfh.jf.intel.com
Fixes: c36e20249571 ("mm: introduce mf_dax_kill_procs() for fsdax case")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory-failure.c |   22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fall-back-to-vma_address-when-notify_failure-fails
+++ a/mm/memory-failure.c
@@ -345,13 +345,17 @@ static unsigned long dev_pagemap_mapping
  * not much we can do.	We just print a message and ignore otherwise.
  */
 
+#define FSDAX_INVALID_PGOFF ULONG_MAX
+
 /*
  * Schedule a process for later kill.
  * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
  *
- * Notice: @fsdax_pgoff is used only when @p is a fsdax page.
- *   In other cases, such as anonymous and file-backend page, the address to be
- *   killed can be caculated by @p itself.
+ * Note: @fsdax_pgoff is used only when @p is a fsdax page and a
+ * filesystem with a memory failure handler has claimed the
+ * memory_failure event. In all other cases, page->index and
+ * page->mapping are sufficient for mapping the page back to its
+ * corresponding user virtual address.
  */
 static void add_to_kill(struct task_struct *tsk, struct page *p,
 			pgoff_t fsdax_pgoff, struct vm_area_struct *vma,
@@ -367,11 +371,7 @@ static void add_to_kill(struct task_stru
 
 	tk->addr = page_address_in_vma(p, vma);
 	if (is_zone_device_page(p)) {
-		/*
-		 * Since page->mapping is not used for fsdax, we need
-		 * calculate the address based on the vma.
-		 */
-		if (p->pgmap->type == MEMORY_DEVICE_FS_DAX)
+		if (fsdax_pgoff != FSDAX_INVALID_PGOFF)
 			tk->addr = vma_pgoff_address(fsdax_pgoff, 1, vma);
 		tk->size_shift = dev_pagemap_mapping_shift(vma, tk->addr);
 	} else
@@ -523,7 +523,8 @@ static void collect_procs_anon(struct pa
 			if (!page_mapped_in_vma(page, vma))
 				continue;
 			if (vma->vm_mm == t->mm)
-				add_to_kill(t, page, 0, vma, to_kill);
+				add_to_kill(t, page, FSDAX_INVALID_PGOFF, vma,
+					    to_kill);
 		}
 	}
 	read_unlock(&tasklist_lock);
@@ -559,7 +560,8 @@ static void collect_procs_file(struct pa
 			 * to be informed of all such data corruptions.
 			 */
 			if (vma->vm_mm == t->mm)
-				add_to_kill(t, page, 0, vma, to_kill);
+				add_to_kill(t, page, FSDAX_INVALID_PGOFF, vma,
+					    to_kill);
 		}
 	}
 	read_unlock(&tasklist_lock);
_

Patches currently in -mm which might be from dan.j.williams@intel.com are

xfs-quiet-notify_failure-eopnotsupp-cases.patch
xfs-fix-sb_born-check-in-xfs_dax_notify_failure.patch
mm-memory-failure-fix-detection-of-memory_failure-handlers.patch
mm-memory-failure-fall-back-to-vma_address-when-notify_failure-fails.patch