From f758eeabeb96f878c860e8f110f94ec8820822a9 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@infradead.org>
Date: Thu, 21 Apr 2011 18:19:44 -0600
Subject: writeback: split inode_wb_list_lock into bdi_writeback.list_lock
Split the global inode_wb_list_lock into a per-bdi_writeback list_lock,
as it's currently the most contended lock in the system for metadata
heavy workloads. It won't help for single-filesystem workloads for
which we'll need the I/O-less balance_dirty_pages, but at least we
can dedicate a cpu to spinning on each bdi now for larger systems.
Based on earlier patches from Nick Piggin and Dave Chinner.
It reduces lock contentions to 1/4 in this test case:
10 HDD JBOD, 100 dd on each disk, XFS, 6GB ram
lock_stat version 0.3
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
class name con-bounces contentions waittime-min waittime-max waittime-total acq-bounces acquisitions holdtime-min holdtime-max holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
vanilla 2.6.39-rc3:
inode_wb_list_lock: 42590 44433 0.12 147.74 144127.35 252274 886792 0.08 121.34 917211.23
------------------
inode_wb_list_lock 2 [<ffffffff81165da5>] bdev_inode_switch_bdi+0x29/0x85
inode_wb_list_lock 34 [<ffffffff8115bd0b>] inode_wb_list_del+0x22/0x49
inode_wb_list_lock 12893 [<ffffffff8115bb53>] __mark_inode_dirty+0x170/0x1d0
inode_wb_list_lock 10702 [<ffffffff8115afef>] writeback_single_inode+0x16d/0x20a
------------------
inode_wb_list_lock 2 [<ffffffff81165da5>] bdev_inode_switch_bdi+0x29/0x85
inode_wb_list_lock 19 [<ffffffff8115bd0b>] inode_wb_list_del+0x22/0x49
inode_wb_list_lock 5550 [<ffffffff8115bb53>] __mark_inode_dirty+0x170/0x1d0
inode_wb_list_lock 8511 [<ffffffff8115b4ad>] writeback_sb_inodes+0x10f/0x157
2.6.39-rc3 + patch:
&(&wb->list_lock)->rlock: 11383 11657 0.14 151.69 40429.51 90825 527918 0.11 145.90 556843.37
------------------------
&(&wb->list_lock)->rlock 10 [<ffffffff8115b189>] inode_wb_list_del+0x5f/0x86
&(&wb->list_lock)->rlock 1493 [<ffffffff8115b1ed>] writeback_inodes_wb+0x3d/0x150
&(&wb->list_lock)->rlock 3652 [<ffffffff8115a8e9>] writeback_sb_inodes+0x123/0x16f
&(&wb->list_lock)->rlock 1412 [<ffffffff8115a38e>] writeback_single_inode+0x17f/0x223
------------------------
&(&wb->list_lock)->rlock 3 [<ffffffff8110b5af>] bdi_lock_two+0x46/0x4b
&(&wb->list_lock)->rlock 6 [<ffffffff8115b189>] inode_wb_list_del+0x5f/0x86
&(&wb->list_lock)->rlock 2061 [<ffffffff8115af97>] __mark_inode_dirty+0x173/0x1cf
&(&wb->list_lock)->rlock 2629 [<ffffffff8115a8e9>] writeback_sb_inodes+0x123/0x16f
hughd@google.com: fix recursive lock when bdi_lock_two() is called with new the same as old
akpm@linux-foundation.org: cleanup bdev_inode_switch_bdi() comment
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
mm/filemap.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/mm/filemap.c b/mm/filemap.c
index d7b10578a64..1e492c3dd6f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -81,7 +81,7 @@
* ->i_mutex
* ->i_alloc_sem (various)
*
- * inode_wb_list_lock
+ * bdi->wb.list_lock
* sb_lock (fs/fs-writeback.c)
* ->mapping->tree_lock (__sync_single_inode)
*
@@ -99,9 +99,9 @@
* ->zone.lru_lock (check_pte_range->isolate_lru_page)
* ->private_lock (page_remove_rmap->set_page_dirty)
* ->tree_lock (page_remove_rmap->set_page_dirty)
- * inode_wb_list_lock (page_remove_rmap->set_page_dirty)
+ * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
* ->inode->i_lock (page_remove_rmap->set_page_dirty)
- * inode_wb_list_lock (zap_pte_range->set_page_dirty)
+ * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
* ->inode->i_lock (zap_pte_range->set_page_dirty)
* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
*
--
cgit v1.2.3-70-g09d2
From 6328650bb4d854a7dc1498d1c0048b838b0d340c Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Wed, 3 Aug 2011 16:21:18 -0700
Subject: radix_tree: exceptional entries and indices
A patchset to extend tmpfs to MAX_LFS_FILESIZE by abandoning its
peculiar swap vector, instead keeping a file's swap entries in the same
radix tree as its struct page pointers: thus saving memory, and
simplifying its code and locking.
This patch:
The radix_tree is used by several subsystems for different purposes. A
major use is to store the struct page pointers of a file's pagecache for
memory management. But what if mm wanted to store something other than
page pointers there too?
The low bit of a radix_tree entry is already used to denote an indirect
pointer, for internal use, and the unlikely radix_tree_deref_retry()
case.
Define the next bit as denoting an exceptional entry, and supply inline
functions radix_tree_exception() to return non-0 in either unlikely
case, and radix_tree_exceptional_entry() to return non-0 in the second
case.
If a subsystem already uses radix_tree with that bit set, no problem: it
does not affect internal workings at all, but is defined for the
convenience of those storing well-aligned pointers in the radix_tree.
The radix_tree_gang_lookups have an implicit assumption that the caller
can deduce the offset of each entry returned e.g. by the page->index of
a struct page. But that may not be feasible for some kinds of item to
be stored there.
radix_tree_gang_lookup_slot() allow for an optional indices argument,
output array in which to return those offsets. The same could be added
to other radix_tree_gang_lookups, but for now keep it to the only one
for which we need it.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/radix-tree.h | 36 +++++++++++++++++++++++++++++++++---
lib/radix-tree.c | 29 +++++++++++++++++++----------
mm/filemap.c | 4 ++--
3 files changed, 54 insertions(+), 15 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 23241c2fecc..b7edf825145 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -39,7 +39,15 @@
* when it is shrunk, before we rcu free the node. See shrink code for
* details.
*/
-#define RADIX_TREE_INDIRECT_PTR 1
+#define RADIX_TREE_INDIRECT_PTR 1
+/*
+ * A common use of the radix tree is to store pointers to struct pages;
+ * but shmem/tmpfs needs also to store swap entries in the same tree:
+ * those are marked as exceptional entries to distinguish them.
+ * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it.
+ */
+#define RADIX_TREE_EXCEPTIONAL_ENTRY 2
+#define RADIX_TREE_EXCEPTIONAL_SHIFT 2
#define radix_tree_indirect_to_ptr(ptr) \
radix_tree_indirect_to_ptr((void __force *)(ptr))
@@ -173,6 +181,28 @@ static inline int radix_tree_deref_retry(void *arg)
return unlikely((unsigned long)arg & RADIX_TREE_INDIRECT_PTR);
}
+/**
+ * radix_tree_exceptional_entry - radix_tree_deref_slot gave exceptional entry?
+ * @arg: value returned by radix_tree_deref_slot
+ * Returns: 0 if well-aligned pointer, non-0 if exceptional entry.
+ */
+static inline int radix_tree_exceptional_entry(void *arg)
+{
+ /* Not unlikely because radix_tree_exception often tested first */
+ return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY;
+}
+
+/**
+ * radix_tree_exception - radix_tree_deref_slot returned either exception?
+ * @arg: value returned by radix_tree_deref_slot
+ * Returns: 0 if well-aligned pointer, non-0 if either kind of exception.
+ */
+static inline int radix_tree_exception(void *arg)
+{
+ return unlikely((unsigned long)arg &
+ (RADIX_TREE_INDIRECT_PTR | RADIX_TREE_EXCEPTIONAL_ENTRY));
+}
+
/**
* radix_tree_replace_slot - replace item in a slot
* @pslot: pointer to slot, returned by radix_tree_lookup_slot
@@ -194,8 +224,8 @@ void *radix_tree_delete(struct radix_tree_root *, unsigned long);
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items);
-unsigned int
-radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
+unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,
+ void ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items);
unsigned long radix_tree_next_hole(struct radix_tree_root *root,
unsigned long index, unsigned long max_scan);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 7ea2e033d71..348eaefbed7 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -823,8 +823,8 @@ unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
EXPORT_SYMBOL(radix_tree_prev_hole);
static unsigned int
-__lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
- unsigned int max_items, unsigned long *next_index)
+__lookup(struct radix_tree_node *slot, void ***results, unsigned long *indices,
+ unsigned long index, unsigned int max_items, unsigned long *next_index)
{
unsigned int nr_found = 0;
unsigned int shift, height;
@@ -857,12 +857,16 @@ __lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
/* Bottom level: grab some items */
for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
- index++;
if (slot->slots[i]) {
- results[nr_found++] = &(slot->slots[i]);
- if (nr_found == max_items)
+ results[nr_found] = &(slot->slots[i]);
+ if (indices)
+ indices[nr_found] = index;
+ if (++nr_found == max_items) {
+ index++;
goto out;
+ }
}
+ index++;
}
out:
*next_index = index;
@@ -918,8 +922,8 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
if (cur_index > max_index)
break;
- slots_found = __lookup(node, (void ***)results + ret, cur_index,
- max_items - ret, &next_index);
+ slots_found = __lookup(node, (void ***)results + ret, NULL,
+ cur_index, max_items - ret, &next_index);
nr_found = 0;
for (i = 0; i < slots_found; i++) {
struct radix_tree_node *slot;
@@ -944,6 +948,7 @@ EXPORT_SYMBOL(radix_tree_gang_lookup);
* radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
* @root: radix tree root
* @results: where the results of the lookup are placed
+ * @indices: where their indices should be placed (but usually NULL)
* @first_index: start the lookup from this key
* @max_items: place up to this many items at *results
*
@@ -958,7 +963,8 @@ EXPORT_SYMBOL(radix_tree_gang_lookup);
* protection, radix_tree_deref_slot may fail requiring a retry.
*/
unsigned int
-radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
+radix_tree_gang_lookup_slot(struct radix_tree_root *root,
+ void ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items)
{
unsigned long max_index;
@@ -974,6 +980,8 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
if (first_index > 0)
return 0;
results[0] = (void **)&root->rnode;
+ if (indices)
+ indices[0] = 0;
return 1;
}
node = indirect_to_ptr(node);
@@ -987,8 +995,9 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
if (cur_index > max_index)
break;
- slots_found = __lookup(node, results + ret, cur_index,
- max_items - ret, &next_index);
+ slots_found = __lookup(node, results + ret,
+ indices ? indices + ret : NULL,
+ cur_index, max_items - ret, &next_index);
ret += slots_found;
if (next_index == 0)
break;
diff --git a/mm/filemap.c b/mm/filemap.c
index 867d40222ec..b83aebfd0a0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -840,7 +840,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
rcu_read_lock();
restart:
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
- (void ***)pages, start, nr_pages);
+ (void ***)pages, NULL, start, nr_pages);
ret = 0;
for (i = 0; i < nr_found; i++) {
struct page *page;
@@ -903,7 +903,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
rcu_read_lock();
restart:
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
- (void ***)pages, index, nr_pages);
+ (void ***)pages, NULL, index, nr_pages);
ret = 0;
for (i = 0; i < nr_found; i++) {
struct page *page;
--
cgit v1.2.3-70-g09d2
From a2c16d6cb0e478812829ca84aeabd02e36af35eb Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Wed, 3 Aug 2011 16:21:19 -0700
Subject: mm: let swap use exceptional entries
If swap entries are to be stored along with struct page pointers in a
radix tree, they need to be distinguished as exceptional entries.
Most of the handling of swap entries in radix tree will be contained in
shmem.c, but a few functions in filemap.c's common code need to check
for their appearance: find_get_page(), find_lock_page(),
find_get_pages() and find_get_pages_contig().
So as not to slow their fast paths, tuck those checks inside the
existing checks for unlikely radix_tree_deref_slot(); except for
find_lock_page(), where it is an added test. And make it a BUG in
find_get_pages_tag(), which is not applied to tmpfs files.
A part of the reason for eliminating shmem_readpage() earlier, was to
minimize the places where common code would need to allow for swap
entries.
The swp_entry_t known to swapfile.c must be massaged into a slightly
different form when stored in the radix tree, just as it gets massaged
into a pte_t when stored in page tables.
In an i386 kernel this limits its information (type and page offset) to
30 bits: given 32 "types" of swapfile and 4kB pagesize, that's a maximum
swapfile size of 128GB. Which is less than the 512GB we previously
allowed with X86_PAE (where the swap entry can occupy the entire upper
32 bits of a pte_t), but not a new limitation on 32-bit without PAE; and
there's not a new limitation on 64-bit (where swap filesize is already
limited to 16TB by a 32-bit page offset). Thirty areas of 128GB is
probably still enough swap for a 64GB 32-bit machine.
Provide swp_to_radix_entry() and radix_to_swp_entry() conversions, and
enforce filesize limit in read_swap_header(), just as for ptes.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/swapops.h | 23 +++++++++++++++++++++++
mm/filemap.c | 49 +++++++++++++++++++++++++++++++------------------
mm/swapfile.c | 20 ++++++++++++--------
3 files changed, 66 insertions(+), 26 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index cd42e30b7c6..2189d3ffc85 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -1,3 +1,8 @@
+#ifndef _LINUX_SWAPOPS_H
+#define _LINUX_SWAPOPS_H
+
+#include <linux/radix-tree.h>
+
/*
* swapcache pages are stored in the swapper_space radix tree. We want to
* get good packing density in that tree, so the index should be dense in
@@ -76,6 +81,22 @@ static inline pte_t swp_entry_to_pte(swp_entry_t entry)
return __swp_entry_to_pte(arch_entry);
}
+static inline swp_entry_t radix_to_swp_entry(void *arg)
+{
+ swp_entry_t entry;
+
+ entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+ return entry;
+}
+
+static inline void *swp_to_radix_entry(swp_entry_t entry)
+{
+ unsigned long value;
+
+ value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
+ return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
+}
+
#ifdef CONFIG_MIGRATION
static inline swp_entry_t make_migration_entry(struct page *page, int write)
{
@@ -169,3 +190,5 @@ static inline int non_swap_entry(swp_entry_t entry)
return 0;
}
#endif
+
+#endif /* _LINUX_SWAPOPS_H */
diff --git a/mm/filemap.c b/mm/filemap.c
index b83aebfd0a0..76bfb6460f5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -714,9 +714,12 @@ repeat:
page = radix_tree_deref_slot(pagep);
if (unlikely(!page))
goto out;
- if (radix_tree_deref_retry(page))
+ if (radix_tree_exception(page)) {
+ if (radix_tree_exceptional_entry(page))
+ goto out;
+ /* radix_tree_deref_retry(page) */
goto repeat;
-
+ }
if (!page_cache_get_speculative(page))
goto repeat;
@@ -753,7 +756,7 @@ struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
repeat:
page = find_get_page(mapping, offset);
- if (page) {
+ if (page && !radix_tree_exception(page)) {
lock_page(page);
/* Has the page been truncated? */
if (unlikely(page->mapping != mapping)) {
@@ -849,11 +852,14 @@ repeat:
if (unlikely(!page))
continue;
- /*
- * This can only trigger when the entry at index 0 moves out
- * of or back to the root: none yet gotten, safe to restart.
- */
- if (radix_tree_deref_retry(page)) {
+ if (radix_tree_exception(page)) {
+ if (radix_tree_exceptional_entry(page))
+ continue;
+ /*
+ * radix_tree_deref_retry(page):
+ * can only trigger when entry at index 0 moves out of
+ * or back to root: none yet gotten, safe to restart.
+ */
WARN_ON(start | i);
goto restart;
}
@@ -912,12 +918,16 @@ repeat:
if (unlikely(!page))
continue;
- /*
- * This can only trigger when the entry at index 0 moves out
- * of or back to the root: none yet gotten, safe to restart.
- */
- if (radix_tree_deref_retry(page))
+ if (radix_tree_exception(page)) {
+ if (radix_tree_exceptional_entry(page))
+ break;
+ /*
+ * radix_tree_deref_retry(page):
+ * can only trigger when entry at index 0 moves out of
+ * or back to root: none yet gotten, safe to restart.
+ */
goto restart;
+ }
if (!page_cache_get_speculative(page))
goto repeat;
@@ -977,12 +987,15 @@ repeat:
if (unlikely(!page))
continue;
- /*
- * This can only trigger when the entry at index 0 moves out
- * of or back to the root: none yet gotten, safe to restart.
- */
- if (radix_tree_deref_retry(page))
+ if (radix_tree_exception(page)) {
+ BUG_ON(radix_tree_exceptional_entry(page));
+ /*
+ * radix_tree_deref_retry(page):
+ * can only trigger when entry at index 0 moves out of
+ * or back to root: none yet gotten, safe to restart.
+ */
goto restart;
+ }
if (!page_cache_get_speculative(page))
goto repeat;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1b8c3390724..17bc224bce6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1924,20 +1924,24 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
/*
* Find out how many pages are allowed for a single swap
- * device. There are two limiting factors: 1) the number of
- * bits for the swap offset in the swp_entry_t type and
- * 2) the number of bits in the a swap pte as defined by
- * the different architectures. In order to find the
- * largest possible bit mask a swap entry with swap type 0
+ * device. There are three limiting factors: 1) the number
+ * of bits for the swap offset in the swp_entry_t type, and
+ * 2) the number of bits in the swap pte as defined by the
+ * the different architectures, and 3) the number of free bits
+ * in an exceptional radix_tree entry. In order to find the
+ * largest possible bit mask, a swap entry with swap type 0
* and swap offset ~0UL is created, encoded to a swap pte,
- * decoded to a swp_entry_t again and finally the swap
+ * decoded to a swp_entry_t again, and finally the swap
* offset is extracted. This will mask all the bits from
* the initial ~0UL mask that can't be encoded in either
* the swp_entry_t or the architecture definition of a
- * swap pte.
+ * swap pte. Then the same is done for a radix_tree entry.
*/
maxpages = swp_offset(pte_to_swp_entry(
- swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+ swp_entry_to_pte(swp_entry(0, ~0UL))));
+ maxpages = swp_offset(radix_to_swp_entry(
+ swp_to_radix_entry(swp_entry(0, maxpages)))) + 1;
+
if (maxpages > swap_header->info.last_page) {
maxpages = swap_header->info.last_page + 1;
/* p->max is an unsigned int: don't overflow it */
--
cgit v1.2.3-70-g09d2
From 31475dd611209413bace21651a400afb91d0bd9d Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Wed, 3 Aug 2011 16:21:27 -0700
Subject: mm: a few small updates for radix-swap
Remove PageSwapBacked (!page_is_file_cache) cases from
add_to_page_cache_locked() and add_to_page_cache_lru(): those pages now
go through shmem_add_to_page_cache().
Remove a comment on maximum tmpfs size from fsstack_copy_inode_size(),
and add a comment on swap entries to invalidate_mapping_pages().
And mincore_page() uses find_get_page() on what might be shmem or a
tmpfs file: allow for a radix_tree_exceptional_entry(), and proceed to
find_get_page() on swapper_space if so (oh, swapper_space needs #ifdef).
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/stack.c | 5 +----
mm/filemap.c | 21 +++------------------
mm/mincore.c | 10 ++++++----
mm/truncate.c | 8 ++++++++
4 files changed, 18 insertions(+), 26 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/fs/stack.c b/fs/stack.c
index 4a6f7f44065..b4f2ab48a61 100644
--- a/fs/stack.c
+++ b/fs/stack.c
@@ -29,10 +29,7 @@ void fsstack_copy_inode_size(struct inode *dst, struct inode *src)
*
* We don't actually know what locking is used at the lower level;
* but if it's a filesystem that supports quotas, it will be using
- * i_lock as in inode_add_bytes(). tmpfs uses other locking, and
- * its 32-bit is (just) able to exceed 2TB i_size with the aid of
- * holes; but its i_blocks cannot carry into the upper long without
- * almost 2TB swap - let's ignore that case.
+ * i_lock as in inode_add_bytes().
*/
if (sizeof(i_blocks) > sizeof(long))
spin_lock(&src->i_lock);
diff --git a/mm/filemap.c b/mm/filemap.c
index 76bfb6460f5..96778faf82d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -33,7 +33,6 @@
#include <linux/cpuset.h>
#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
#include <linux/memcontrol.h>
-#include <linux/mm_inline.h> /* for page_is_file_cache() */
#include <linux/cleancache.h>
#include "internal.h"
@@ -462,6 +461,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
int error;
VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(PageSwapBacked(page));
error = mem_cgroup_cache_charge(page, current->mm,
gfp_mask & GFP_RECLAIM_MASK);
@@ -479,8 +479,6 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
if (likely(!error)) {
mapping->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
- if (PageSwapBacked(page))
- __inc_zone_page_state(page, NR_SHMEM);
spin_unlock_irq(&mapping->tree_lock);
} else {
page->mapping = NULL;
@@ -502,22 +500,9 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
{
int ret;
- /*
- * Splice_read and readahead add shmem/tmpfs pages into the page cache
- * before shmem_readpage has a chance to mark them as SwapBacked: they
- * need to go on the anon lru below, and mem_cgroup_cache_charge
- * (called in add_to_page_cache) needs to know where they're going too.
- */
- if (mapping_cap_swap_backed(mapping))
- SetPageSwapBacked(page);
-
ret = add_to_page_cache(page, mapping, offset, gfp_mask);
- if (ret == 0) {
- if (page_is_file_cache(page))
- lru_cache_add_file(page);
- else
- lru_cache_add_anon(page);
- }
+ if (ret == 0)
+ lru_cache_add_file(page);
return ret;
}
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
diff --git a/mm/mincore.c b/mm/mincore.c
index a4e6b9d75c7..733f1829b0d 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -69,12 +69,14 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
* file will not get a swp_entry_t in its pte, but rather it is like
* any other file mapping (ie. marked !present and faulted in with
* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
- *
- * However when tmpfs moves the page from pagecache and into swapcache,
- * it is still in core, but the find_get_page below won't find it.
- * No big deal, but make a note of it.
*/
page = find_get_page(mapping, pgoff);
+#ifdef CONFIG_SWAP
+ if (radix_tree_exceptional_entry(page)) {
+ swp_entry_t swap = radix_to_swp_entry(page);
+ page = find_get_page(&swapper_space, swap.val);
+ }
+#endif
if (page) {
present = PageUptodate(page);
page_cache_release(page);
diff --git a/mm/truncate.c b/mm/truncate.c
index 232eb2736a7..b40ac6d4e86 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -336,6 +336,14 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
unsigned long count = 0;
int i;
+ /*
+ * Note: this function may get called on a shmem/tmpfs mapping:
+ * pagevec_lookup() might then return 0 prematurely (because it
+ * got a gangful of swap entries); but it's hardly worth worrying
+ * about - it can rarely have anything to free from such a mapping
+ * (most pages are dirty), and already skips over any difficulties.
+ */
+
pagevec_init(&pvec, 0);
while (index <= end && pagevec_lookup(&pvec, mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
--
cgit v1.2.3-70-g09d2
From 8079b1c859c44f27d63da4951f5038a16589a563 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Wed, 3 Aug 2011 16:21:28 -0700
Subject: mm: clarify the radix_tree exceptional cases
Make the radix_tree exceptional cases, mostly in filemap.c, clearer.
It's hard to devise a suitable snappy name that illuminates the use by
shmem/tmpfs for swap, while keeping filemap/pagecache/radix_tree
generality. And akpm points out that /* radix_tree_deref_retry(page) */
comments look like calls that have been commented out for unknown
reason.
Skirt the naming difficulty by rearranging these blocks to handle the
transient radix_tree_deref_retry(page) case first; then just explain the
remaining shmem/tmpfs swap case in a comment.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/filemap.c | 66 ++++++++++++++++++++++++++++++++++++++++--------------------
mm/mincore.c | 1 +
mm/shmem.c | 12 +++++++----
3 files changed, 53 insertions(+), 26 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/mm/filemap.c b/mm/filemap.c
index 96778faf82d..645a080ba4d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -700,10 +700,14 @@ repeat:
if (unlikely(!page))
goto out;
if (radix_tree_exception(page)) {
- if (radix_tree_exceptional_entry(page))
- goto out;
- /* radix_tree_deref_retry(page) */
- goto repeat;
+ if (radix_tree_deref_retry(page))
+ goto repeat;
+ /*
+ * Otherwise, shmem/tmpfs must be storing a swap entry
+ * here as an exceptional entry: so return it without
+ * attempting to raise page count.
+ */
+ goto out;
}
if (!page_cache_get_speculative(page))
goto repeat;
@@ -838,15 +842,21 @@ repeat:
continue;
if (radix_tree_exception(page)) {
- if (radix_tree_exceptional_entry(page))
- continue;
+ if (radix_tree_deref_retry(page)) {
+ /*
+ * Transient condition which can only trigger
+ * when entry at index 0 moves out of or back
+ * to root: none yet gotten, safe to restart.
+ */
+ WARN_ON(start | i);
+ goto restart;
+ }
/*
- * radix_tree_deref_retry(page):
- * can only trigger when entry at index 0 moves out of
- * or back to root: none yet gotten, safe to restart.
+ * Otherwise, shmem/tmpfs must be storing a swap entry
+ * here as an exceptional entry: so skip over it -
+ * we only reach this from invalidate_mapping_pages().
*/
- WARN_ON(start | i);
- goto restart;
+ continue;
}
if (!page_cache_get_speculative(page))
@@ -904,14 +914,20 @@ repeat:
continue;
if (radix_tree_exception(page)) {
- if (radix_tree_exceptional_entry(page))
- break;
+ if (radix_tree_deref_retry(page)) {
+ /*
+ * Transient condition which can only trigger
+ * when entry at index 0 moves out of or back
+ * to root: none yet gotten, safe to restart.
+ */
+ goto restart;
+ }
/*
- * radix_tree_deref_retry(page):
- * can only trigger when entry at index 0 moves out of
- * or back to root: none yet gotten, safe to restart.
+ * Otherwise, shmem/tmpfs must be storing a swap entry
+ * here as an exceptional entry: so stop looking for
+ * contiguous pages.
*/
- goto restart;
+ break;
}
if (!page_cache_get_speculative(page))
@@ -973,13 +989,19 @@ repeat:
continue;
if (radix_tree_exception(page)) {
- BUG_ON(radix_tree_exceptional_entry(page));
+ if (radix_tree_deref_retry(page)) {
+ /*
+ * Transient condition which can only trigger
+ * when entry at index 0 moves out of or back
+ * to root: none yet gotten, safe to restart.
+ */
+ goto restart;
+ }
/*
- * radix_tree_deref_retry(page):
- * can only trigger when entry at index 0 moves out of
- * or back to root: none yet gotten, safe to restart.
+ * This function is never used on a shmem/tmpfs
+ * mapping, so a swap entry won't be found here.
*/
- goto restart;
+ BUG();
}
if (!page_cache_get_speculative(page))
diff --git a/mm/mincore.c b/mm/mincore.c
index 733f1829b0d..636a86876ff 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -72,6 +72,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
*/
page = find_get_page(mapping, pgoff);
#ifdef CONFIG_SWAP
+ /* shmem/tmpfs may return swap: account for swapcache page too. */
if (radix_tree_exceptional_entry(page)) {
swp_entry_t swap = radix_to_swp_entry(page);
page = find_get_page(&swapper_space, swap.val);
diff --git a/mm/shmem.c b/mm/shmem.c
index 1c702f6f124..32f6763f16f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -332,10 +332,14 @@ repeat:
if (unlikely(!page))
continue;
if (radix_tree_exception(page)) {
- if (radix_tree_exceptional_entry(page))
- goto export;
- /* radix_tree_deref_retry(page) */
- goto restart;
+ if (radix_tree_deref_retry(page))
+ goto restart;
+ /*
+ * Otherwise, we must be storing a swap entry
+ * here as an exceptional entry: so return it
+ * without attempting to raise page count.
+ */
+ goto export;
}
if (!page_cache_get_speculative(page))
goto repeat;
--
cgit v1.2.3-70-g09d2
From cc39c6a9bbdebfcf1a7dee64d83bf302bc38d941 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shaohua.li@intel.com>
Date: Thu, 15 Sep 2011 08:45:19 +0800
Subject: mm: account skipped entries to avoid looping in find_get_pages
The found entries by find_get_pages() could be all swap entries. In
this case we skip the entries, but make sure the skipped entries are
accounted, so we don't keep looping.
Using nr_found > nr_skip to simplify code as suggested by Eric.
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/filemap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
(limited to 'mm/filemap.c')
diff --git a/mm/filemap.c b/mm/filemap.c
index 645a080ba4d..7771871fa35 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -827,13 +827,14 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
{
unsigned int i;
unsigned int ret;
- unsigned int nr_found;
+ unsigned int nr_found, nr_skip;
rcu_read_lock();
restart:
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
(void ***)pages, NULL, start, nr_pages);
ret = 0;
+ nr_skip = 0;
for (i = 0; i < nr_found; i++) {
struct page *page;
repeat:
@@ -856,6 +857,7 @@ repeat:
* here as an exceptional entry: so skip over it -
* we only reach this from invalidate_mapping_pages().
*/
+ nr_skip++;
continue;
}
@@ -876,7 +878,7 @@ repeat:
* If all entries were removed before we could secure them,
* try again, because callers stop trying once 0 is returned.
*/
- if (unlikely(!ret && nr_found))
+ if (unlikely(!ret && nr_found > nr_skip))
goto restart;
rcu_read_unlock();
return ret;
--
cgit v1.2.3-70-g09d2