+ mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch added to mm-unstable branch

+ mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: move FAULT_FLAG_VMA_LOCK check down from do_fault()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch

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

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: move FAULT_FLAG_VMA_LOCK check down from do_fault()
Date: Mon, 24 Jul 2023 19:54:07 +0100

Perform the check at the start of do_read_fault(), do_cow_fault() and
do_shared_fault() instead.  Should be no performance change from the last
commit.

Link: https://lkml.kernel.org/r/20230724185410.1124082-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

--- a/mm/memory.c~mm-move-fault_flag_vma_lock-check-down-from-do_fault
+++ a/mm/memory.c
@@ -4659,6 +4659,11 @@ static vm_fault_t do_read_fault(struct v
 	vm_fault_t ret = 0;
 	struct folio *folio;
 
+	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+		vma_end_read(vmf->vma);
+		return VM_FAULT_RETRY;
+	}
+
 	/*
 	 * Let's call ->map_pages() first and use ->fault() as fallback
 	 * if page by the offset is not ready to be mapped (cold cache or
@@ -4687,6 +4692,11 @@ static vm_fault_t do_cow_fault(struct vm
 	struct vm_area_struct *vma = vmf->vma;
 	vm_fault_t ret;
 
+	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+		vma_end_read(vma);
+		return VM_FAULT_RETRY;
+	}
+
 	if (unlikely(anon_vma_prepare(vma)))
 		return VM_FAULT_OOM;
 
@@ -4727,6 +4737,11 @@ static vm_fault_t do_shared_fault(struct
 	vm_fault_t ret, tmp;
 	struct folio *folio;
 
+	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+		vma_end_read(vma);
+		return VM_FAULT_RETRY;
+	}
+
 	ret = __do_fault(vmf);
 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
 		return ret;
@@ -4773,11 +4788,6 @@ static vm_fault_t do_fault(struct vm_fau
 	struct mm_struct *vm_mm = vma->vm_mm;
 	vm_fault_t ret;
 
-	if (vmf->flags & FAULT_FLAG_VMA_LOCK){
-		vma_end_read(vma);
-		return VM_FAULT_RETRY;
-	}
-
 	/*
 	 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
 	 */
_

Patches currently in -mm which might be from willy@infradead.org are

rmap-pass-the-folio-to-__page_check_anon_rmap.patch
highmem-add-memcpy_to_folio-and-memcpy_from_folio.patch
affs-convert-affs_symlink_read_folio-to-use-the-folio.patch
affs-convert-data-read-and-write-to-use-folios.patch
migrate-use-folio_set_bh-instead-of-set_bh_page.patch
ntfs3-convert-ntfs_get_block_vbo-to-use-a-folio.patch
jbd2-use-a-folio-in-jbd2_journal_write_metadata_buffer.patch
buffer-remove-set_bh_page.patch
zswap-make-zswap_store-take-a-folio.patch
memcg-convert-get_obj_cgroup_from_page-to-get_obj_cgroup_from_folio.patch
swap-remove-some-calls-to-compound_head-in-swap_readpage.patch
zswap-make-zswap_load-take-a-folio.patch
mm-remove-config_per_vma_lock-ifdefs.patch
mm-allow-per-vma-locks-on-file-backed-vmas.patch
mm-move-fault_flag_vma_lock-check-from-handle_mm_fault.patch
mm-handle-pud-faults-under-the-vma-lock.patch
mm-handle-some-pmd-faults-under-the-vma-lock.patch
mm-move-fault_flag_vma_lock-check-down-in-handle_pte_fault.patch
mm-move-fault_flag_vma_lock-check-down-from-do_fault.patch
mm-run-the-fault-around-code-under-the-vma-lock.patch
mm-handle-swap-and-numa-pte-faults-under-the-vma-lock.patch
mm-handle-faults-that-merely-update-the-accessed-bit-under-the-vma-lock.patch