nilfs2: fix lock order reversal in nilfs_clean_segments ioctl
This is a companion patch to ("nilfs2: fix possible circular locking
for get information ioctls").
This corrects lock order reversal between mm->mmap_sem and
nilfs->ns_segctor_sem in nilfs_clean_segments() which was detected by
lockdep check:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.30-rc3-nilfs-00003-g360bdc1 #7
-------------------------------------------------------
mmap/5294 is trying to acquire lock:
(&nilfs->ns_segctor_sem){++++.+}, at: [<d0d0e846>] nilfs_transaction_begin+0xb6/0x10c [nilfs2]
but task is already holding lock:
(&mm->mmap_sem){++++++}, at: [<c043700a>] do_page_fault+0x1d8/0x30a
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&mm->mmap_sem){++++++}:
[<c01470a5>] __lock_acquire+0x1066/0x13b0
[<c01474a9>] lock_acquire+0xba/0xdd
[<c01836bc>] might_fault+0x68/0x88
[<c023c61d>] copy_from_user+0x2a/0x111
[<d0d120d0>] nilfs_ioctl_prepare_clean_segments+0x1d/0xf1 [nilfs2]
[<d0d0e2aa>] nilfs_clean_segments+0x6d/0x1b9 [nilfs2]
[<d0d11f68>] nilfs_ioctl+0x2ad/0x318 [nilfs2]
[<c01a3be7>] vfs_ioctl+0x22/0x69
[<c01a408e>] do_vfs_ioctl+0x460/0x499
[<c01a4107>] sys_ioctl+0x40/0x5a
[<c01031a4>] sysenter_do_call+0x12/0x38
[<ffffffff>] 0xffffffff
-> #0 (&nilfs->ns_segctor_sem){++++.+}:
[<c0146e0b>] __lock_acquire+0xdcc/0x13b0
[<c01474a9>] lock_acquire+0xba/0xdd
[<c0433f1d>] down_read+0x2a/0x3e
[<d0d0e846>] nilfs_transaction_begin+0xb6/0x10c [nilfs2]
[<d0cfe0e5>] nilfs_page_mkwrite+0xe7/0x154 [nilfs2]
[<c0183b0b>] __do_fault+0x165/0x376
[<c01855cd>] handle_mm_fault+0x287/0x5d1
[<c043712d>] do_page_fault+0x2fb/0x30a
[<c0435462>] error_code+0x72/0x78
[<ffffffff>] 0xffffffff
where nilfs_clean_segments() holds:
nilfs->ns_segctor_sem -> copy_from_user()
--> page fault -> mm->mmap_sem
And, page fault path may hold:
page fault -> mm->mmap_sem
--> nilfs_page_mkwrite() -> nilfs->ns_segctor_sem
Even though nilfs_clean_segments() does not perform write access on
given user pages, it may cause deadlock because nilfs->ns_segctor_sem
is shared per device and mm->mmap_sem can be shared with other tasks.
To avoid this problem, this patch moves all calls of copy_from_user()
outside the nilfs->ns_segctor_sem lock in the ioctl.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi
Родитель
47eb6b9c8f
Коммит
4f6b828837
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@ -25,6 +25,7 @@
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#include <linux/smp_lock.h> /* lock_kernel(), unlock_kernel() */
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#include <linux/capability.h> /* capable() */
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#include <linux/uaccess.h> /* copy_from_user(), copy_to_user() */
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#include <linux/vmalloc.h>
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#include <linux/nilfs2_fs.h>
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#include "nilfs.h"
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#include "segment.h"
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@ -297,10 +298,10 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
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return 0;
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}
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static ssize_t
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nilfs_ioctl_do_move_blocks(struct the_nilfs *nilfs, __u64 *posp, int flags,
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void *buf, size_t size, size_t nmembs)
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static int nilfs_ioctl_move_blocks(struct the_nilfs *nilfs,
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struct nilfs_argv *argv, void *buf)
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{
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size_t nmembs = argv->v_nmembs;
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struct inode *inode;
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struct nilfs_vdesc *vdesc;
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struct buffer_head *bh, *n;
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@ -361,19 +362,10 @@ nilfs_ioctl_do_move_blocks(struct the_nilfs *nilfs, __u64 *posp, int flags,
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return ret;
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}
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static inline int nilfs_ioctl_move_blocks(struct the_nilfs *nilfs,
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struct nilfs_argv *argv,
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int dir)
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{
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return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
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nilfs_ioctl_do_move_blocks);
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}
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static ssize_t
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nilfs_ioctl_do_delete_checkpoints(struct the_nilfs *nilfs, __u64 *posp,
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int flags, void *buf, size_t size,
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size_t nmembs)
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static int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs,
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struct nilfs_argv *argv, void *buf)
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{
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size_t nmembs = argv->v_nmembs;
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struct inode *cpfile = nilfs->ns_cpfile;
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struct nilfs_period *periods = buf;
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int ret, i;
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@ -387,36 +379,21 @@ nilfs_ioctl_do_delete_checkpoints(struct the_nilfs *nilfs, __u64 *posp,
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return nmembs;
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}
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static inline int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs,
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struct nilfs_argv *argv,
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int dir)
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static int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs,
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struct nilfs_argv *argv, void *buf)
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{
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return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
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nilfs_ioctl_do_delete_checkpoints);
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}
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size_t nmembs = argv->v_nmembs;
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int ret;
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static ssize_t
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nilfs_ioctl_do_free_vblocknrs(struct the_nilfs *nilfs, __u64 *posp, int flags,
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void *buf, size_t size, size_t nmembs)
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{
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int ret = nilfs_dat_freev(nilfs_dat_inode(nilfs), buf, nmembs);
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ret = nilfs_dat_freev(nilfs_dat_inode(nilfs), buf, nmembs);
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return (ret < 0) ? ret : nmembs;
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}
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static inline int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs,
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struct nilfs_argv *argv,
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int dir)
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{
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return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
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nilfs_ioctl_do_free_vblocknrs);
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}
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static ssize_t
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nilfs_ioctl_do_mark_blocks_dirty(struct the_nilfs *nilfs, __u64 *posp,
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int flags, void *buf, size_t size,
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size_t nmembs)
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static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs,
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struct nilfs_argv *argv, void *buf)
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{
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size_t nmembs = argv->v_nmembs;
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struct inode *dat = nilfs_dat_inode(nilfs);
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struct nilfs_bmap *bmap = NILFS_I(dat)->i_bmap;
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struct nilfs_bdesc *bdescs = buf;
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@ -455,18 +432,10 @@ nilfs_ioctl_do_mark_blocks_dirty(struct the_nilfs *nilfs, __u64 *posp,
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return nmembs;
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}
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static inline int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs,
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struct nilfs_argv *argv,
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int dir)
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{
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return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
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nilfs_ioctl_do_mark_blocks_dirty);
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}
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static ssize_t
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nilfs_ioctl_do_free_segments(struct the_nilfs *nilfs, __u64 *posp, int flags,
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void *buf, size_t size, size_t nmembs)
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static int nilfs_ioctl_free_segments(struct the_nilfs *nilfs,
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struct nilfs_argv *argv, void *buf)
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{
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size_t nmembs = argv->v_nmembs;
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struct nilfs_sb_info *sbi = nilfs->ns_writer;
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int ret;
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@ -481,31 +450,19 @@ nilfs_ioctl_do_free_segments(struct the_nilfs *nilfs, __u64 *posp, int flags,
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return (ret < 0) ? ret : nmembs;
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}
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static inline int nilfs_ioctl_free_segments(struct the_nilfs *nilfs,
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struct nilfs_argv *argv,
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int dir)
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{
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return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
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nilfs_ioctl_do_free_segments);
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}
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int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
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void __user *argp)
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struct nilfs_argv *argv, void **kbufs)
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{
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struct nilfs_argv argv[5];
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const char *msg;
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int dir, ret;
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int ret;
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if (copy_from_user(argv, argp, sizeof(argv)))
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return -EFAULT;
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dir = _IOC_WRITE;
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ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], dir);
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ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], kbufs[0]);
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if (ret < 0) {
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msg = "cannot read source blocks";
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goto failed;
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}
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ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], dir);
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ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], kbufs[1]);
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if (ret < 0) {
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/*
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* can safely abort because checkpoints can be removed
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@ -514,7 +471,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
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msg = "cannot delete checkpoints";
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goto failed;
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}
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ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], dir);
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ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], kbufs[2]);
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if (ret < 0) {
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/*
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* can safely abort because DAT file is updated atomically
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@ -523,7 +480,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
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msg = "cannot delete virtual blocks from DAT file";
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goto failed;
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}
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ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], dir);
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ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], kbufs[3]);
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if (ret < 0) {
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/*
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* can safely abort because the operation is nondestructive.
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@ -531,7 +488,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
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msg = "cannot mark copying blocks dirty";
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goto failed;
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}
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ret = nilfs_ioctl_free_segments(nilfs, &argv[4], dir);
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ret = nilfs_ioctl_free_segments(nilfs, &argv[4], kbufs[4]);
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if (ret < 0) {
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/*
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* can safely abort because this operation is atomic.
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@ -551,9 +508,75 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
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static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
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unsigned int cmd, void __user *argp)
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{
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struct nilfs_argv argv[5];
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const static size_t argsz[5] = {
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sizeof(struct nilfs_vdesc),
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sizeof(struct nilfs_period),
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sizeof(__u64),
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sizeof(struct nilfs_bdesc),
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sizeof(__u64),
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};
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void __user *base;
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void *kbufs[5];
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struct the_nilfs *nilfs;
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size_t len, nsegs;
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int n, ret;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return nilfs_clean_segments(inode->i_sb, argp);
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if (copy_from_user(argv, argp, sizeof(argv)))
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return -EFAULT;
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nsegs = argv[4].v_nmembs;
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if (argv[4].v_size != argsz[4])
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return -EINVAL;
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/*
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* argv[4] points to segment numbers this ioctl cleans. We
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* use kmalloc() for its buffer because memory used for the
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* segment numbers is enough small.
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*/
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kbufs[4] = memdup_user((void __user *)(unsigned long)argv[4].v_base,
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nsegs * sizeof(__u64));
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if (IS_ERR(kbufs[4]))
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return PTR_ERR(kbufs[4]);
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nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
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for (n = 0; n < 4; n++) {
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ret = -EINVAL;
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if (argv[n].v_size != argsz[n])
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goto out_free;
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if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
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goto out_free;
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len = argv[n].v_size * argv[n].v_nmembs;
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base = (void __user *)(unsigned long)argv[n].v_base;
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if (len == 0) {
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kbufs[n] = NULL;
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continue;
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}
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kbufs[n] = vmalloc(len);
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if (!kbufs[n]) {
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ret = -ENOMEM;
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goto out_free;
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}
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if (copy_from_user(kbufs[n], base, len)) {
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ret = -EFAULT;
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vfree(kbufs[n]);
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goto out_free;
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}
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}
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ret = nilfs_clean_segments(inode->i_sb, argv, kbufs);
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out_free:
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while (--n > 0)
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vfree(kbufs[n]);
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kfree(kbufs[4]);
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return ret;
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}
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static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
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@ -236,7 +236,8 @@ extern int nilfs_sync_file(struct file *, struct dentry *, int);
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/* ioctl.c */
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long nilfs_ioctl(struct file *, unsigned int, unsigned long);
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int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, void __user *);
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int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, struct nilfs_argv *,
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void **);
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/* inode.c */
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extern struct inode *nilfs_new_inode(struct inode *, int);
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@ -2589,7 +2589,8 @@ nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
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}
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}
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int nilfs_clean_segments(struct super_block *sb, void __user *argp)
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int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
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void **kbufs)
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{
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struct nilfs_sb_info *sbi = NILFS_SB(sb);
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struct nilfs_sc_info *sci = NILFS_SC(sbi);
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@ -2606,7 +2607,7 @@ int nilfs_clean_segments(struct super_block *sb, void __user *argp)
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err = nilfs_init_gcdat_inode(nilfs);
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if (unlikely(err))
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goto out_unlock;
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err = nilfs_ioctl_prepare_clean_segments(nilfs, argp);
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err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
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if (unlikely(err))
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goto out_unlock;
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@ -222,7 +222,8 @@ extern int nilfs_construct_segment(struct super_block *);
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extern int nilfs_construct_dsync_segment(struct super_block *, struct inode *,
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loff_t, loff_t);
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extern void nilfs_flush_segment(struct super_block *, ino_t);
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extern int nilfs_clean_segments(struct super_block *, void __user *);
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extern int nilfs_clean_segments(struct super_block *, struct nilfs_argv *,
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void **);
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extern int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *,
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__u64 *, size_t);
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