The patch titled
Subject: mm: introduce vma detached flag
has been added to the -mm mm-unstable branch. Its filename is
mm-introduce-vma-detached-flag.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-vma-detached-flag.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@xxxxxxxxxx>
Subject: mm: introduce vma detached flag
Date: Mon, 27 Feb 2023 09:36:21 -0800
Per-vma locking mechanism will search for VMA under RCU protection and
then after locking it, has to ensure it was not removed from the VMA tree
after we found it. To make this check efficient, introduce a
vma->detached flag to mark VMAs which were removed from the VMA tree.
Link: https://lkml.kernel.org/r/20230227173632.3292573-23-surenb@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/include/linux/mm.h~mm-introduce-vma-detached-flag
+++ a/include/linux/mm.h
@@ -693,6 +693,14 @@ static inline void vma_assert_write_lock
VM_BUG_ON_VMA(vma->vm_lock_seq != READ_ONCE(vma->vm_mm->mm_lock_seq), vma);
}
+static inline void vma_mark_detached(struct vm_area_struct *vma, bool detached)
+{
+ /* When detaching vma should be write-locked */
+ if (detached)
+ vma_assert_write_locked(vma);
+ vma->detached = detached;
+}
+
#else /* CONFIG_PER_VMA_LOCK */
static inline void vma_init_lock(struct vm_area_struct *vma) {}
@@ -701,6 +709,8 @@ static inline bool vma_start_read(struct
static inline void vma_end_read(struct vm_area_struct *vma) {}
static inline void vma_start_write(struct vm_area_struct *vma) {}
static inline void vma_assert_write_locked(struct vm_area_struct *vma) {}
+static inline void vma_mark_detached(struct vm_area_struct *vma,
+ bool detached) {}
#endif /* CONFIG_PER_VMA_LOCK */
@@ -712,6 +722,7 @@ static inline void vma_init(struct vm_ar
vma->vm_mm = mm;
vma->vm_ops = &dummy_vm_ops;
INIT_LIST_HEAD(&vma->anon_vma_chain);
+ vma_mark_detached(vma, false);
vma_init_lock(vma);
}
--- a/include/linux/mm_types.h~mm-introduce-vma-detached-flag
+++ a/include/linux/mm_types.h
@@ -511,6 +511,9 @@ struct vm_area_struct {
#ifdef CONFIG_PER_VMA_LOCK
int vm_lock_seq;
struct rw_semaphore lock;
+
+ /* Flag to indicate areas detached from the mm->mm_mt tree */
+ bool detached;
#endif
/*
--- a/mm/mmap.c~mm-introduce-vma-detached-flag
+++ a/mm/mmap.c
@@ -600,6 +600,7 @@ static inline void vma_complete(struct v
if (vp->remove) {
again:
+ vma_mark_detached(vp->remove, true);
if (vp->file) {
uprobe_munmap(vp->remove, vp->remove->vm_start,
vp->remove->vm_end);
@@ -2261,6 +2262,7 @@ static inline int munmap_sidetree(struct
if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
return -ENOMEM;
+ vma_mark_detached(vma, true);
if (vma->vm_flags & VM_LOCKED)
vma->vm_mm->locked_vm -= vma_pages(vma);
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx 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-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-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
per-vma-locks.patch
