Pages pinned to block group_descriptors in the super_block are non-reclaimable.
Those pages are showed up as file-backed in meminfo which confuse user program
issuing too many drop_caches/ttfp when this memory will never be freed.
The change has us not account for the file system descriptors by taking the pages
off LRU and decrementing the NR_FILE_PAGES counter. The pages are putting back when
the filesystem is being unmounted.
Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>
---
fs/buffer.c | 44 +++++++++++++++++++++++++++++++++++++++++++
fs/ext2/super.c | 15 +++++++++++++-
fs/ext4/super.c | 12 ++++++++++-
include/linux/buffer_head.h | 5 ++++
4 files changed, 74 insertions(+), 2 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 3e7dca2..677d5f1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -22,6 +22,8 @@
#include <linux/syscalls.h>
#include <linux/fs.h>
#include <linux/mm.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/capability.h>
@@ -3314,6 +3316,48 @@ int bh_submit_read(struct buffer_head *bh)
}
EXPORT_SYMBOL(bh_submit_read);
+void bh_disable_accounting(struct buffer_head *bh)
+{
+ struct page *page = bh->b_page;
+ struct zone *zone = page_zone(page);
+ unsigned long flags;
+
+ if (buffer_unaccounted(bh))
+ return;
+
+ spin_lock_irqsave(&zone->lru_lock, flags);
+ /* If someone else is holding it off-LRU we can't safely do anything */
+ if (PageLRU(page)) {
+ BUG_ON(buffer_unaccounted(bh));
+ ClearPageLRU(page);
+ del_page_from_lru(zone, page);
+ __dec_zone_state(zone, NR_FILE_PAGES);
+ set_buffer_unaccounted(bh);
+ }
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+}
+EXPORT_SYMBOL(bh_disable_accounting);
+
+void bh_enable_accounting(struct buffer_head *bh)
+{
+ struct page *page = bh->b_page;
+ struct zone *zone = page_zone(page);
+ unsigned long flags;
+
+ if (!buffer_unaccounted(bh))
+ return;
+
+ spin_lock_irqsave(&zone->lru_lock, flags);
+ if (buffer_unaccounted(bh)) {
+ SetPageLRU(page);
+ add_page_to_lru_list(zone, page, LRU_INACTIVE_FILE);
+ __inc_zone_state(zone, NR_FILE_PAGES);
+ clear_buffer_unaccounted(bh);
+ }
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+}
+EXPORT_SYMBOL(bh_enable_accounting);
+
void __init buffer_init(void)
{
int nrpages;
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 1ec6026..a4d21ce 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -29,6 +29,7 @@
#include <linux/vfs.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
+#include <linux/swap.h>
#include <linux/log2.h>
#include <linux/quotaops.h>
#include <asm/uaccess.h>
@@ -135,13 +136,16 @@ static void ext2_put_super (struct super_block * sb)
}
db_count = sbi->s_gdb_count;
for (i = 0; i < db_count; i++)
- if (sbi->s_group_desc[i])
+ if (sbi->s_group_desc[i]) {
+ bh_enable_accounting(sbi->s_group_desc[i]);
brelse (sbi->s_group_desc[i]);
+ }
kfree(sbi->s_group_desc);
kfree(sbi->s_debts);
percpu_counter_destroy(&sbi->s_freeblocks_counter);
percpu_counter_destroy(&sbi->s_freeinodes_counter);
percpu_counter_destroy(&sbi->s_dirs_counter);
+ bh_enable_accounting(sbi->s_sbh);
brelse (sbi->s_sbh);
sb->s_fs_info = NULL;
kfree(sbi->s_blockgroup_lock);
@@ -1080,9 +1084,18 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
ext2_msg(sb, KERN_WARNING,
"warning: mounting ext3 filesystem as ext2");
+
if (ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY))
sb->s_flags |= MS_RDONLY;
ext2_write_super(sb);
+
+ /* disable accounting of pinned file pages */
+ lru_add_drain_all();
+ db_count = sbi->s_gdb_count;
+ for (i = 0; i < db_count; i++)
+ bh_disable_accounting(sbi->s_group_desc[i]);
+ bh_disable_accounting(sbi->s_sbh);
+
return 0;
cantfind_ext2:
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2614774..5203476 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -32,6 +32,7 @@
#include <linux/vfs.h>
#include <linux/random.h>
#include <linux/mount.h>
+#include <linux/swap.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/seq_file.h>
@@ -734,8 +735,10 @@ static void ext4_put_super(struct super_block *sb)
}
kobject_del(&sbi->s_kobj);
- for (i = 0; i < sbi->s_gdb_count; i++)
+ for (i = 0; i < sbi->s_gdb_count; i++) {
+ bh_enable_accounting(sbi->s_group_desc[i]);
brelse(sbi->s_group_desc[i]);
+ }
kfree(sbi->s_group_desc);
if (is_vmalloc_addr(sbi->s_flex_groups))
vfree(sbi->s_flex_groups);
@@ -745,6 +748,7 @@ static void ext4_put_super(struct super_block *sb)
percpu_counter_destroy(&sbi->s_freeinodes_counter);
percpu_counter_destroy(&sbi->s_dirs_counter);
percpu_counter_destroy(&sbi->s_dirtyblocks_counter);
+ bh_enable_accounting(sbi->s_sbh);
brelse(sbi->s_sbh);
#ifdef CONFIG_QUOTA
for (i = 0; i < MAXQUOTAS; i++)
@@ -3129,6 +3133,12 @@ no_journal:
goto failed_mount4;
}
+ /* disable accounting of pinned file pages */
+ lru_add_drain_all();
+ for (i = 0; i < db_count; i++)
+ bh_disable_accounting(sbi->s_group_desc[i]);
+ bh_disable_accounting(sbi->s_sbh);
+
sbi->s_kobj.kset = ext4_kset;
init_completion(&sbi->s_kobj_unregister);
err = kobject_init_and_add(&sbi->s_kobj, &ext4_ktype, NULL,
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index ec94c12..7d48499 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -34,6 +34,7 @@ enum bh_state_bits {
BH_Write_EIO, /* I/O error on write */
BH_Eopnotsupp, /* operation not supported (barrier) */
BH_Unwritten, /* Buffer is allocated on disk but not written */
+ BH_Unaccounted, /* Backing page has been removed from accounting */
BH_Quiet, /* Buffer Error Prinks to be quiet */
BH_PrivateStart,/* not a state bit, but the first bit available
@@ -126,6 +127,7 @@ BUFFER_FNS(Boundary, boundary)
BUFFER_FNS(Write_EIO, write_io_error)
BUFFER_FNS(Eopnotsupp, eopnotsupp)
BUFFER_FNS(Unwritten, unwritten)
+BUFFER_FNS(Unaccounted, unaccounted)
#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
#define touch_buffer(bh) mark_page_accessed(bh->b_page)
@@ -234,6 +236,9 @@ int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
int nobh_writepage(struct page *page, get_block_t *get_block,
struct writeback_control *wbc);
+void bh_disable_accounting(struct buffer_head *bh);
+void bh_enable_accounting(struct buffer_head *bh);
+
void buffer_init(void);
/*
--
1.7.1
--
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