Re: 3.5.1 ext4_ sleeping while atomic bug.
Hi Dave,
Thanks for the bug report! The following should address the bug which
you found.
- Ted
>From 05ca87aa00121756b5d41f3d71eb8b51bed3bc92 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o
Date: Fri, 10 Aug 2012 13:57:52 -0400
Subject: [PATCH] ext4: don't call ext4_error while block group is locked
While in ext4_validate_block_bitmap(), if an block allocation bitmap
is found to be invalid, we call ext4_error() while the block group is
still locked. This causes ext4_commit_super() to call a function
which might sleep while in an atomic context.
There's no need to keep the block group locked at this point, so hoist
the ext4_error() call up to ext4_validate_block_bitmap() and release
the block group spinlock before calling ext4_error().
The reported stack trace can be found at:
http://article.gmane.org/gmane.comp.file-systems.ext4/33731
Reported-by: Dave Jones
Signed-off-by: "Theodore Ts'o"
Cc: sta...@vger.kernel.org
---
fs/ext4/balloc.c | 62 +---
fs/ext4/bitmap.c | 1 -
2 files changed, 37 insertions(+), 26 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d23b31c..1b50890 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -280,14 +280,18 @@ struct ext4_group_desc * ext4_get_group_desc(struct
super_block *sb,
return desc;
}
-static int ext4_valid_block_bitmap(struct super_block *sb,
- struct ext4_group_desc *desc,
- unsigned int block_group,
- struct buffer_head *bh)
+/*
+ * Return the block number which was discovered to be invalid, or 0 if
+ * the block bitmap is valid.
+ */
+static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
{
ext4_grpblk_t offset;
ext4_grpblk_t next_zero_bit;
- ext4_fsblk_t bitmap_blk;
+ ext4_fsblk_t blk;
ext4_fsblk_t group_first_block;
if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
@@ -297,37 +301,33 @@ static int ext4_valid_block_bitmap(struct super_block *sb,
* or it has to also read the block group where the bitmaps
* are located to verify they are set.
*/
- return 1;
+ return 0;
}
group_first_block = ext4_group_first_block_no(sb, block_group);
/* check whether block bitmap block number is set */
- bitmap_blk = ext4_block_bitmap(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_block_bitmap(sb, desc);
+ offset = blk - group_first_block;
if (!ext4_test_bit(offset, bh->b_data))
/* bad block bitmap */
- goto err_out;
+ return blk;
/* check whether the inode bitmap block number is set */
- bitmap_blk = ext4_inode_bitmap(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_inode_bitmap(sb, desc);
+ offset = blk - group_first_block;
if (!ext4_test_bit(offset, bh->b_data))
/* bad block bitmap */
- goto err_out;
+ return blk;
/* check whether the inode table block number is set */
- bitmap_blk = ext4_inode_table(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_inode_table(sb, desc);
+ offset = blk - group_first_block;
next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
offset + EXT4_SB(sb)->s_itb_per_group,
offset);
- if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
- /* good bitmap for inode tables */
- return 1;
-
-err_out:
- ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
- block_group, bitmap_blk);
+ if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
+ /* bad bitmap for inode tables */
+ return blk;
return 0;
}
@@ -336,14 +336,26 @@ void ext4_validate_block_bitmap(struct super_block *sb,
unsigned int block_group,
struct buffer_head *bh)
{
+ ext4_fsblk_tblk;
+
if (buffer_verified(bh))
return;
ext4_lock_group(sb, block_group);
- if (ext4_valid_block_bitmap(sb, desc, block_group, bh) &&
- ext4_block_bitmap_csum_verify(sb, block_group, desc, bh,
- EXT4_BLOCKS_PER_GROUP(sb) / 8))
- set_buffer_verified(bh);
+ blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
+ if (unlikely(blk != 0)) {
+
Re: 3.5.1 ext4_ sleeping while atomic bug.
Hi Dave,
Thanks for the bug report! The following should address the bug which
you found.
- Ted
From 05ca87aa00121756b5d41f3d71eb8b51bed3bc92 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o ty...@mit.edu
Date: Fri, 10 Aug 2012 13:57:52 -0400
Subject: [PATCH] ext4: don't call ext4_error while block group is locked
While in ext4_validate_block_bitmap(), if an block allocation bitmap
is found to be invalid, we call ext4_error() while the block group is
still locked. This causes ext4_commit_super() to call a function
which might sleep while in an atomic context.
There's no need to keep the block group locked at this point, so hoist
the ext4_error() call up to ext4_validate_block_bitmap() and release
the block group spinlock before calling ext4_error().
The reported stack trace can be found at:
http://article.gmane.org/gmane.comp.file-systems.ext4/33731
Reported-by: Dave Jones da...@redhat.com
Signed-off-by: Theodore Ts'o ty...@mit.edu
Cc: sta...@vger.kernel.org
---
fs/ext4/balloc.c | 62 +---
fs/ext4/bitmap.c | 1 -
2 files changed, 37 insertions(+), 26 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d23b31c..1b50890 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -280,14 +280,18 @@ struct ext4_group_desc * ext4_get_group_desc(struct
super_block *sb,
return desc;
}
-static int ext4_valid_block_bitmap(struct super_block *sb,
- struct ext4_group_desc *desc,
- unsigned int block_group,
- struct buffer_head *bh)
+/*
+ * Return the block number which was discovered to be invalid, or 0 if
+ * the block bitmap is valid.
+ */
+static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
{
ext4_grpblk_t offset;
ext4_grpblk_t next_zero_bit;
- ext4_fsblk_t bitmap_blk;
+ ext4_fsblk_t blk;
ext4_fsblk_t group_first_block;
if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
@@ -297,37 +301,33 @@ static int ext4_valid_block_bitmap(struct super_block *sb,
* or it has to also read the block group where the bitmaps
* are located to verify they are set.
*/
- return 1;
+ return 0;
}
group_first_block = ext4_group_first_block_no(sb, block_group);
/* check whether block bitmap block number is set */
- bitmap_blk = ext4_block_bitmap(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_block_bitmap(sb, desc);
+ offset = blk - group_first_block;
if (!ext4_test_bit(offset, bh-b_data))
/* bad block bitmap */
- goto err_out;
+ return blk;
/* check whether the inode bitmap block number is set */
- bitmap_blk = ext4_inode_bitmap(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_inode_bitmap(sb, desc);
+ offset = blk - group_first_block;
if (!ext4_test_bit(offset, bh-b_data))
/* bad block bitmap */
- goto err_out;
+ return blk;
/* check whether the inode table block number is set */
- bitmap_blk = ext4_inode_table(sb, desc);
- offset = bitmap_blk - group_first_block;
+ blk = ext4_inode_table(sb, desc);
+ offset = blk - group_first_block;
next_zero_bit = ext4_find_next_zero_bit(bh-b_data,
offset + EXT4_SB(sb)-s_itb_per_group,
offset);
- if (next_zero_bit = offset + EXT4_SB(sb)-s_itb_per_group)
- /* good bitmap for inode tables */
- return 1;
-
-err_out:
- ext4_error(sb, Invalid block bitmap - block_group = %d, block = %llu,
- block_group, bitmap_blk);
+ if (next_zero_bit offset + EXT4_SB(sb)-s_itb_per_group)
+ /* bad bitmap for inode tables */
+ return blk;
return 0;
}
@@ -336,14 +336,26 @@ void ext4_validate_block_bitmap(struct super_block *sb,
unsigned int block_group,
struct buffer_head *bh)
{
+ ext4_fsblk_tblk;
+
if (buffer_verified(bh))
return;
ext4_lock_group(sb, block_group);
- if (ext4_valid_block_bitmap(sb, desc, block_group, bh)
- ext4_block_bitmap_csum_verify(sb, block_group, desc, bh,
- EXT4_BLOCKS_PER_GROUP(sb) / 8))
- set_buffer_verified(bh);
+ blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
+ if
3.5.1 ext4_ sleeping while atomic bug.
BUG: sleeping function called from invalid context at
include/linux/buffer_head.h:333
in_atomic(): 1, irqs_disabled(): 0, pid: 9894, name: fstest
3 locks held by fstest/9894:
#0: (>i_mutex_dir_key#4/1){+.+.+.}, at: []
kern_path_create+0x7e/0x140
#1: (>i_data_sem){..}, at: []
ext4_map_blocks+0xb6/0x250
#2: (&(>locks[i].lock)->rlock){+.+...}, at: []
ext4_validate_block_bitmap+0x77/0x230
Pid: 9894, comm: fstest Not tainted 3.5.1-1.fc17.x86_64.debug #1
Call Trace:
[] __might_sleep+0x18a/0x240
[] __sync_dirty_buffer+0x30/0xf0
[] sync_dirty_buffer+0x13/0x20
[] ext4_commit_super+0x1e8/0x260
[] save_error_info+0x23/0x30
[] __ext4_error+0x89/0xa0
[] ? ext4_validate_block_bitmap+0x77/0x230
[] ext4_validate_block_bitmap+0x1bb/0x230
[] ext4_read_block_bitmap_nowait+0x8e/0x3b0
[] ext4_mb_init_cache+0x160/0x990
[] ? trace_hardirqs_on_caller+0x10d/0x1a0
[] ext4_mb_init_group+0x126/0x250
[] ext4_mb_good_group+0x116/0x130
[] ext4_mb_regular_allocator+0x1a3/0x420
[] ? kmem_cache_alloc+0xe0/0x290
[] ext4_mb_new_blocks+0x4f1/0xb90
[] ? __find_get_block+0xaf/0x220
[] ext4_alloc_branch+0x42e/0x690
[] ? _raw_spin_unlock_irq+0x30/0x50
[] ext4_ind_map_blocks+0x1e7/0x990
[] ? down_write+0x9a/0xb0
[] ? ext4_map_blocks+0xb6/0x250
[] ext4_map_blocks+0xe5/0x250
[] ext4_getblk+0x5b/0x1f0
[] ext4_bread+0x18/0xa0
[] ext4_mkdir+0x147/0x3d0
[] vfs_mkdir+0xa6/0x130
[] sys_mkdirat+0xbe/0xd0
[] sys_mkdir+0x19/0x20
[] system_call_fastpath+0x16/0x1b
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3.5.1 ext4_ sleeping while atomic bug.
BUG: sleeping function called from invalid context at
include/linux/buffer_head.h:333
in_atomic(): 1, irqs_disabled(): 0, pid: 9894, name: fstest
3 locks held by fstest/9894:
#0: (type-i_mutex_dir_key#4/1){+.+.+.}, at: [811d5dae]
kern_path_create+0x7e/0x140
#1: (ei-i_data_sem){..}, at: [81252e76]
ext4_map_blocks+0xb6/0x250
#2: ((bgl-locks[i].lock)-rlock){+.+...}, at: [8124a5e7]
ext4_validate_block_bitmap+0x77/0x230
Pid: 9894, comm: fstest Not tainted 3.5.1-1.fc17.x86_64.debug #1
Call Trace:
[8109cd0a] __might_sleep+0x18a/0x240
[811fb430] __sync_dirty_buffer+0x30/0xf0
[811fb503] sync_dirty_buffer+0x13/0x20
[81273018] ext4_commit_super+0x1e8/0x260
[81273283] save_error_info+0x23/0x30
[81274539] __ext4_error+0x89/0xa0
[8124a5e7] ? ext4_validate_block_bitmap+0x77/0x230
[8124a72b] ext4_validate_block_bitmap+0x1bb/0x230
[8124b0ae] ext4_read_block_bitmap_nowait+0x8e/0x3b0
[812891c0] ext4_mb_init_cache+0x160/0x990
[810d16bd] ? trace_hardirqs_on_caller+0x10d/0x1a0
[81289b16] ext4_mb_init_group+0x126/0x250
[81289d56] ext4_mb_good_group+0x116/0x130
[8128c493] ext4_mb_regular_allocator+0x1a3/0x420
[811aa920] ? kmem_cache_alloc+0xe0/0x290
[8128e2c1] ext4_mb_new_blocks+0x4f1/0xb90
[811fad9f] ? __find_get_block+0xaf/0x220
[81293e7e] ext4_alloc_branch+0x42e/0x690
[816c6030] ? _raw_spin_unlock_irq+0x30/0x50
[812949a7] ext4_ind_map_blocks+0x1e7/0x990
[816c348a] ? down_write+0x9a/0xb0
[81252e76] ? ext4_map_blocks+0xb6/0x250
[81252ea5] ext4_map_blocks+0xe5/0x250
[8125306b] ext4_getblk+0x5b/0x1f0
[81253218] ext4_bread+0x18/0xa0
[8125e527] ext4_mkdir+0x147/0x3d0
[811d2536] vfs_mkdir+0xa6/0x130
[811d6c6e] sys_mkdirat+0xbe/0xd0
[811d6c99] sys_mkdir+0x19/0x20
[816cefe9] system_call_fastpath+0x16/0x1b
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