+ mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them-fix.patch added to mm-unstable branch

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

The patch titled
     Subject: mm/mmap: remove unnecessary vp->vma check in vma_prepare
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them-fix.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: Suren Baghdasaryan <surenb@google.com>
Subject: mm/mmap: remove unnecessary vp->vma check in vma_prepare
Date: Tue, 28 Feb 2023 18:27:19 -0800

vp->vma in vma_prepare() is always non-NULL, therefore checking it is not
necessary.  Remove the extra check.

Link: https://lkml.kernel.org/r/20230301022720.1380780-1-surenb@google.com
Fixes: e8f071350ea5 ("mm/mmap: write-lock VMAs in vma_prepare before modifying them")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
  Link: https://lore.kernel.org/r/202302281802.J93Nma7q-lkp@intel.com/
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Laurent Dufour <laurent.dufour@fr.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/mm/mmap.c~mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them-fix
+++ a/mm/mmap.c
@@ -502,8 +502,7 @@ static inline void init_vma_prep(struct
  */
 static inline void vma_prepare(struct vma_prepare *vp)
 {
-	if (vp->vma)
-		vma_start_write(vp->vma);
+	vma_start_write(vp->vma);
 	if (vp->adj_next)
 		vma_start_write(vp->adj_next);
 	/* vp->insert is always a newly created VMA, no need for locking */
_

Patches currently in -mm which might be from surenb@google.com are

mm-introduce-config_per_vma_lock.patch
mm-move-mmap_lock-assert-function-definitions.patch
mm-add-per-vma-lock-and-helper-functions-to-control-it.patch
mm-mark-vma-as-being-written-when-changing-vm_flags.patch
mm-mmap-move-vma_prepare-before-vma_adjust_trans_huge.patch
mm-khugepaged-write-lock-vma-while-collapsing-a-huge-page.patch
mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them.patch
mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them-fix.patch
mm-mremap-write-lock-vma-while-remapping-it-to-a-new-address-range.patch
mm-write-lock-vmas-before-removing-them-from-vma-tree.patch
mm-write-lock-vmas-before-removing-them-from-vma-tree-fix.patch
mm-conditionally-write-lock-vma-in-free_pgtables.patch
kernel-fork-assert-no-vma-readers-during-its-destruction.patch
mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch
mm-introduce-vma-detached-flag.patch
mm-introduce-lock_vma_under_rcu-to-be-used-from-arch-specific-code.patch
mm-fall-back-to-mmap_lock-if-vma-anon_vma-is-not-yet-set.patch
mm-add-fault_flag_vma_lock-flag.patch
mm-prevent-do_swap_page-from-handling-page-faults-under-vma-lock.patch
mm-prevent-userfaults-to-be-handled-under-per-vma-lock.patch
mm-introduce-per-vma-lock-statistics.patch
x86-mm-try-vma-lock-based-page-fault-handling-first.patch
arm64-mm-try-vma-lock-based-page-fault-handling-first.patch
mm-mmap-free-vm_area_struct-without-call_rcu-in-exit_mmap.patch
mm-separate-vma-lock-from-vm_area_struct.patch