+ mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback.patch added to mm-hotfixes-unstable branch

+ mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/memory: return vm_fault_t result from migrate_to_ram() callback
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback.patch

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

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------------------------------------------------------
From: Alistair Popple <apopple@nvidia.com>
Subject: mm/memory: return vm_fault_t result from migrate_to_ram() callback
Date: Mon, 14 Nov 2022 22:55:37 +1100

The migrate_to_ram() callback should always succeed, but in rare cases can
fail usually returning VM_FAULT_SIGBUS.  Commit 16ce101db85d
("mm/memory.c: fix race when faulting a device private page") incorrectly
stopped passing the return code up the stack.  Fix this by setting the ret
variable, restoring the previous behaviour on migrate_to_ram() failure.

Link: https://lkml.kernel.org/r/20221114115537.727371-1-apopple@nvidia.com
Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memory.c~mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback
+++ a/mm/memory.c
@@ -3762,7 +3762,7 @@ vm_fault_t do_swap_page(struct vm_fault
 			 */
 			get_page(vmf->page);
 			pte_unmap_unlock(vmf->pte, vmf->ptl);
-			vmf->page->pgmap->ops->migrate_to_ram(vmf);
+			ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
 			put_page(vmf->page);
 		} else if (is_hwpoison_entry(entry)) {
 			ret = VM_FAULT_HWPOISON;
_

Patches currently in -mm which might be from apopple@nvidia.com are

mm-memory-return-vm_fault_t-result-from-migrate_to_ram-callback.patch
mm-khugepaged-refactor-mm_khugepaged_scan_file-tracepoint-to-remove-filename-from-function-call-fix.patch