The commit is pushed to "branch-rh7-3.10.0-1160.6.1.vz7.171.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.6.1.vz7.171.1
------>
commit 33149e68cd1be429dbfc2c4a66019b2b971f7268
Author: Davidlohr Bueso <d...@stgolabs.net>
Date: Thu Dec 3 11:40:47 2020 +0300
ms/mm: convert i_mmap_mutex to rwsem
The i_mmap_mutex is a close cousin of the anon vma lock, both protecting
similar data, one for file backed pages and the other for anon memory. To
this end, this lock can also be a rwsem. In addition, there are some
important opportunities to share the lock when there are no tree
modifications.
This conversion is straightforward. For now, all users take the write
lock.
[s...@canb.auug.org.au: update fremap.c]
Signed-off-by: Davidlohr Bueso <dbu...@suse.de>
Reviewed-by: Rik van Riel <r...@redhat.com>
Acked-by: "Kirill A. Shutemov" <kir...@shutemov.name>
Acked-by: Hugh Dickins <hu...@google.com>
Cc: Oleg Nesterov <o...@redhat.com>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgor...@suse.de>
Signed-off-by: Stephen Rothwell <s...@canb.auug.org.au>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
https://jira.sw.ru/browse/PSBM-122663
(cherry picked from commit c8c06efa8b552608493b7066c234cfa82c47fcea)
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
Documentation/vm/locking | 2 +-
fs/hugetlbfs/inode.c | 10 +++++-----
fs/inode.c | 2 +-
include/linux/fs.h | 7 ++++---
include/linux/mmu_notifier.h | 2 +-
kernel/events/uprobes.c | 2 +-
mm/filemap.c | 10 +++++-----
mm/hugetlb.c | 10 +++++-----
mm/memory.c | 2 +-
mm/mmap.c | 6 +++---
mm/mremap.c | 2 +-
mm/rmap.c | 4 ++--
12 files changed, 30 insertions(+), 29 deletions(-)
diff --git a/Documentation/vm/locking b/Documentation/vm/locking
index f61228b..fb64028 100644
--- a/Documentation/vm/locking
+++ b/Documentation/vm/locking
@@ -66,7 +66,7 @@ in some cases it is not really needed. Eg, vm_start is
modified by
expand_stack(), it is hard to come up with a destructive scenario without
having the vmlist protection in this case.
-The page_table_lock nests with the inode i_mmap_mutex and the kmem cache
+The page_table_lock nests with the inode i_mmap_rwsem and the kmem cache
c_spinlock spinlocks. This is okay, since the kmem code asks for pages after
dropping c_spinlock. The page_table_lock also nests with pagecache_lock and
pagemap_lru_lock spinlocks, and no code asks for memory with these locks
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 79c34c8..c1eef50 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -757,12 +757,12 @@ static struct inode *hugetlbfs_get_root(struct
super_block *sb,
}
/*
- * Hugetlbfs is not reclaimable; therefore its i_mmap_mutex will never
+ * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
* be taken from reclaim -- unlike regular filesystems. This needs an
* annotation because huge_pmd_share() does an allocation under hugetlb's
- * i_mmap_mutex.
+ * i_mmap_rwsem.
*/
-struct lock_class_key hugetlbfs_i_mmap_mutex_key;
+static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
static struct inode *hugetlbfs_get_inode(struct super_block *sb,
struct inode *dir,
@@ -779,8 +779,8 @@ static struct inode *hugetlbfs_get_inode(struct super_block
*sb,
if (inode) {
inode->i_ino = get_next_ino();
inode_init_owner(inode, dir, mode);
- lockdep_set_class(&inode->i_mapping->i_mmap_mutex,
- &hugetlbfs_i_mmap_mutex_key);
+ lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
+ &hugetlbfs_i_mmap_rwsem_key);
inode->i_mapping->a_ops = &hugetlbfs_aops;
inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
diff --git a/fs/inode.c b/fs/inode.c
index 3fec88e..72a9073 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -356,7 +356,7 @@ void address_space_init_once(struct address_space *mapping)
memset(mapping, 0, sizeof(*mapping));
INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
spin_lock_init(&mapping->tree_lock);
- mutex_init(&mapping->i_mmap_mutex);
+ init_rwsem(&mapping->i_mmap_rwsem);
INIT_LIST_HEAD(&mapping->private_list);
spin_lock_init(&mapping->private_lock);
mapping->i_mmap = RB_ROOT;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d570b02..1ea2a23 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -17,6 +17,7 @@
#include <linux/pid.h>
#include <linux/bug.h>
#include <linux/mutex.h>
+#include <linux/rwsem.h>
#include <linux/capability.h>
#include <linux/semaphore.h>
#include <linux/fiemap.h>
@@ -626,7 +627,7 @@ struct address_space {
RH_KABI_REPLACE(unsigned int i_mmap_writable,
atomic_t i_mmap_writable) /* count VM_SHARED mappings
*/
struct rb_root i_mmap; /* tree of private and shared
mappings */
- struct mutex i_mmap_mutex; /* protect tree, count, list */
+ struct rw_semaphore i_mmap_rwsem; /* protect tree, count, list */
/* Protected by tree_lock together with the radix tree */
unsigned long nrpages; /* number of total pages */
/* number of shadow or DAX exceptional entries */
@@ -700,12 +701,12 @@ int mapping_tagged(struct address_space *mapping, int
tag);
static inline void i_mmap_lock_write(struct address_space *mapping)
{
- mutex_lock(&mapping->i_mmap_mutex);
+ down_write(&mapping->i_mmap_rwsem);
}
static inline void i_mmap_unlock_write(struct address_space *mapping)
{
- mutex_unlock(&mapping->i_mmap_mutex);
+ up_write(&mapping->i_mmap_rwsem);
}
/*
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 156b150..ebcd0b4 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -218,7 +218,7 @@ struct mmu_notifier_rhel7 {
* Therefore notifier chains can only be traversed when either
*
* 1. mmap_sem is held.
- * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->rwsem).
+ * 2. One of the reverse map locks is held (i_mmap_rwsem or anon_vma->rwsem).
* 3. No other concurrent thread can access the list (release)
*/
struct mmu_notifier {
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 6c714b0..a7c557f 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -697,7 +697,7 @@ build_map_info(struct address_space *mapping, loff_t
offset, bool is_register)
if (!prev && !more) {
/*
- * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion
through
+ * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion
through
* reclaim. This is optimistic, no harm done if it
fails.
*/
prev = kmalloc(sizeof(struct map_info),
diff --git a/mm/filemap.c b/mm/filemap.c
index 2bd5ca4..950d92b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -66,16 +66,16 @@
/*
* Lock ordering:
*
- * ->i_mmap_mutex (truncate_pagecache)
+ * ->i_mmap_rwsem (truncate_pagecache)
* ->private_lock (__free_pte->__set_page_dirty_buffers)
* ->swap_lock (exclusive_swap_page, others)
* ->mapping->tree_lock
*
* ->i_mutex
- * ->i_mmap_mutex (truncate->unmap_mapping_range)
+ * ->i_mmap_rwsem (truncate->unmap_mapping_range)
*
* ->mmap_sem
- * ->i_mmap_mutex
+ * ->i_mmap_rwsem
* ->page_table_lock or pte_lock (various, mainly in memory.c)
* ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
*
@@ -89,7 +89,7 @@
* sb_lock (fs/fs-writeback.c)
* ->mapping->tree_lock (__sync_single_inode)
*
- * ->i_mmap_mutex
+ * ->i_mmap_rwsem
* ->anon_vma.lock (vma_adjust)
*
* ->anon_vma.lock
@@ -109,7 +109,7 @@
* ->inode->i_lock (zap_pte_range->set_page_dirty)
* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
*
- * ->i_mmap_mutex
+ * ->i_mmap_rwsem
* ->tasklist_lock (memory_failure, collect_procs_ao)
*/
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dd751e3..8300a7f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3515,9 +3515,9 @@ void __unmap_hugepage_range_final(struct mmu_gather *tlb,
* on its way out. We're lucky that the flag has such an appropriate
* name, and can in fact be safely cleared here. We could clear it
* before the __unmap_hugepage_range above, but all that's necessary
- * is to clear it before releasing the i_mmap_mutex. This works
+ * is to clear it before releasing the i_mmap_rwsem. This works
* because in the context this is called, the VMA is about to be
- * destroyed and the i_mmap_mutex is held.
+ * destroyed and the i_mmap_rwsem is held.
*/
vma->vm_flags &= ~VM_MAYSHARE;
}
@@ -4456,9 +4456,9 @@ unsigned long hugetlb_change_protection(struct
vm_area_struct *vma,
spin_unlock(ptl);
}
/*
- * Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare
+ * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
* may have cleared our pud entry and done put_page on the page table:
- * once we release i_mmap_mutex, another task can do the final put_page
+ * once we release i_mmap_rwsem, another task can do the final put_page
* and that page table be reused and filled with junk.
*/
flush_tlb_range(vma, start, end);
@@ -4658,7 +4658,7 @@ static bool vma_shareable(struct vm_area_struct *vma,
unsigned long addr)
* and returns the corresponding pte. While this is not necessary for the
* !shared pmd case because we can allocate the pmd later as well, it makes the
* code much cleaner. pmd allocation is essential for the shared case because
- * pud has to be populated inside the same i_mmap_mutex section - otherwise
+ * pud has to be populated inside the same i_mmap_rwsem section - otherwise
* racing tasks could either miss the sharing (see huge_pte_offset) or select a
* bad pmd for sharing.
*/
diff --git a/mm/memory.c b/mm/memory.c
index 8f7736d..ac2d668 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4360,7 +4360,7 @@ restart:
spin_unlock(&inode->i_lock);
}
- mutex_lock_nested(&peer->i_mmap_mutex, SINGLE_DEPTH_NESTING);
+ down_write_nested(&peer->i_mmap_rwsem, SINGLE_DEPTH_NESTING);
if (!peer->i_peer_file) {
i_mmap_unlock_write(peer);
goto restart;
diff --git a/mm/mmap.c b/mm/mmap.c
index 837a1ac..e515507 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -248,7 +248,7 @@ error:
}
/*
- * Requires inode->i_mapping->i_mmap_mutex
+ * Requires inode->i_mapping->i_mmap_rwsem
*/
static void __remove_shared_vm_struct(struct vm_area_struct *vma,
struct file *file, struct address_space *mapping)
@@ -3200,7 +3200,7 @@ void exit_mmap(struct mm_struct *mm)
/* Insert vm structure into process list sorted by address
* and into the inode's i_mmap tree. If vm_file is non-NULL
- * then i_mmap_mutex is taken here.
+ * then i_mmap_rwsem is taken here.
*/
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
{
@@ -3476,7 +3476,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct
address_space *mapping)
*/
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
BUG();
- mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
+ down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
}
}
diff --git a/mm/mremap.c b/mm/mremap.c
index 3e50a89..b9d487f 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -117,7 +117,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t
*old_pmd,
unsigned long len = old_end - old_addr;
/*
- * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma
+ * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
* locks to ensure that rmap will always observe either the old or the
* new ptes. This is the easiest way to avoid races with
* truncate_pagecache(), page migration, etc...
diff --git a/mm/rmap.c b/mm/rmap.c
index 478f384..e72be32c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1716,14 +1716,14 @@ static int rmap_walk_file(struct page *page, struct
rmap_walk_control *rwc)
* The page lock not only makes sure that page->mapping cannot
* suddenly be NULLified by truncation, it makes sure that the
* structure at mapping cannot be freed and reused yet,
- * so we can safely take mapping->i_mmap_mutex.
+ * so we can safely take mapping->i_mmap_rwsem.
*/
VM_BUG_ON(!PageLocked(page));
if (!mapping)
return ret;
pgoff = page_to_pgoff(page);
- mutex_lock_nested(&mapping->i_mmap_mutex, SINGLE_DEPTH_NESTING);
+ down_write_nested(&mapping->i_mmap_rwsem, SINGLE_DEPTH_NESTING);
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
unsigned long address = vma_address(page, vma);
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