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Commit c8c06efa authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

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.

[sfr@canb.auug.org.au: update fremap.c]
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatar"Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 83cde9e8

fs/hugetlbfs/inode.c

+5 −5
Original line number Diff line number Diff line
@@ -472,12 +472,12 @@ 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

 * i_mmap_mutex.

 * i_mmap_rwsem.

 */

static 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,
@@ -495,8 +495,8 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, 
		struct hugetlbfs_inode_info *info;

		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;

fs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -346,7 +346,7 @@ 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;

include/linux/fs.h

+4 −3
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#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>
@@ -401,7 +402,7 @@ struct address_space { 
	atomic_t		i_mmap_writable;/* count VM_SHARED mappings */

	struct rb_root		i_mmap;		/* tree of private and shared mappings */

	struct list_head	i_mmap_nonlinear;/*list VM_NONLINEAR 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 */

	unsigned long		nrshadows;	/* number of shadow entries */
@@ -469,12 +470,12 @@ 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);

}



/*

include/linux/mmu_notifier.h

+1 −1
Original line number Diff line number Diff line
@@ -154,7 +154,7 @@ struct mmu_notifier_ops { 
 * 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 {

kernel/events/uprobes.c

+1 −1
Original line number Diff line number Diff line
@@ -731,7 +731,7 @@ 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),