From 4f6b828837b4e3836f2c9ac2f0eab9773b6c1327 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Sun, 10 May 2009 22:41:43 +0900 Subject: [PATCH] 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: [] nilfs_transaction_begin+0xb6/0x10c [nilfs2] but task is already holding lock: (&mm->mmap_sem){++++++}, at: [] 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){++++++}: [] __lock_acquire+0x1066/0x13b0 [] lock_acquire+0xba/0xdd [] might_fault+0x68/0x88 [] copy_from_user+0x2a/0x111 [] nilfs_ioctl_prepare_clean_segments+0x1d/0xf1 [nilfs2] [] nilfs_clean_segments+0x6d/0x1b9 [nilfs2] [] nilfs_ioctl+0x2ad/0x318 [nilfs2] [] vfs_ioctl+0x22/0x69 [] do_vfs_ioctl+0x460/0x499 [] sys_ioctl+0x40/0x5a [] sysenter_do_call+0x12/0x38 [] 0xffffffff -> #0 (&nilfs->ns_segctor_sem){++++.+}: [] __lock_acquire+0xdcc/0x13b0 [] lock_acquire+0xba/0xdd [] down_read+0x2a/0x3e [] nilfs_transaction_begin+0xb6/0x10c [nilfs2] [] nilfs_page_mkwrite+0xe7/0x154 [nilfs2] [] __do_fault+0x165/0x376 [] handle_mm_fault+0x287/0x5d1 [] do_page_fault+0x2fb/0x30a [] error_code+0x72/0x78 [] 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 --- fs/nilfs2/ioctl.c | 163 ++++++++++++++++++++++++++++++---------------------- fs/nilfs2/nilfs.h | 3 +- fs/nilfs2/segment.c | 5 +- fs/nilfs2/segment.h | 3 +- 4 files changed, 100 insertions(+), 74 deletions(-) diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c index e3c693d..49489f6 100644 --- a/fs/nilfs2/ioctl.c +++ b/fs/nilfs2/ioctl.c @@ -25,6 +25,7 @@ #include /* lock_kernel(), unlock_kernel() */ #include /* capable() */ #include /* copy_from_user(), copy_to_user() */ +#include #include #include "nilfs.h" #include "segment.h" @@ -297,10 +298,10 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode, return 0; } -static ssize_t -nilfs_ioctl_do_move_blocks(struct the_nilfs *nilfs, __u64 *posp, int flags, - void *buf, size_t size, size_t nmembs) +static int nilfs_ioctl_move_blocks(struct the_nilfs *nilfs, + struct nilfs_argv *argv, void *buf) { + size_t nmembs = argv->v_nmembs; struct inode *inode; struct nilfs_vdesc *vdesc; struct buffer_head *bh, *n; @@ -361,19 +362,10 @@ nilfs_ioctl_do_move_blocks(struct the_nilfs *nilfs, __u64 *posp, int flags, return ret; } -static inline int nilfs_ioctl_move_blocks(struct the_nilfs *nilfs, - struct nilfs_argv *argv, - int dir) -{ - return nilfs_ioctl_wrap_copy(nilfs, argv, dir, - nilfs_ioctl_do_move_blocks); -} - -static ssize_t -nilfs_ioctl_do_delete_checkpoints(struct the_nilfs *nilfs, __u64 *posp, - int flags, void *buf, size_t size, - size_t nmembs) +static int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs, + struct nilfs_argv *argv, void *buf) { + size_t nmembs = argv->v_nmembs; struct inode *cpfile = nilfs->ns_cpfile; struct nilfs_period *periods = buf; int ret, i; @@ -387,36 +379,21 @@ nilfs_ioctl_do_delete_checkpoints(struct the_nilfs *nilfs, __u64 *posp, return nmembs; } -static inline int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs, - struct nilfs_argv *argv, - int dir) +static int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs, + struct nilfs_argv *argv, void *buf) { - return nilfs_ioctl_wrap_copy(nilfs, argv, dir, - nilfs_ioctl_do_delete_checkpoints); -} + size_t nmembs = argv->v_nmembs; + int ret; -static ssize_t -nilfs_ioctl_do_free_vblocknrs(struct the_nilfs *nilfs, __u64 *posp, int flags, - void *buf, size_t size, size_t nmembs) -{ - int ret = nilfs_dat_freev(nilfs_dat_inode(nilfs), buf, nmembs); + ret = nilfs_dat_freev(nilfs_dat_inode(nilfs), buf, nmembs); return (ret < 0) ? ret : nmembs; } -static inline int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs, - struct nilfs_argv *argv, - int dir) -{ - return nilfs_ioctl_wrap_copy(nilfs, argv, dir, - nilfs_ioctl_do_free_vblocknrs); -} - -static ssize_t -nilfs_ioctl_do_mark_blocks_dirty(struct the_nilfs *nilfs, __u64 *posp, - int flags, void *buf, size_t size, - size_t nmembs) +static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs, + struct nilfs_argv *argv, void *buf) { + size_t nmembs = argv->v_nmembs; struct inode *dat = nilfs_dat_inode(nilfs); struct nilfs_bmap *bmap = NILFS_I(dat)->i_bmap; struct nilfs_bdesc *bdescs = buf; @@ -455,18 +432,10 @@ nilfs_ioctl_do_mark_blocks_dirty(struct the_nilfs *nilfs, __u64 *posp, return nmembs; } -static inline int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs, - struct nilfs_argv *argv, - int dir) -{ - return nilfs_ioctl_wrap_copy(nilfs, argv, dir, - nilfs_ioctl_do_mark_blocks_dirty); -} - -static ssize_t -nilfs_ioctl_do_free_segments(struct the_nilfs *nilfs, __u64 *posp, int flags, - void *buf, size_t size, size_t nmembs) +static int nilfs_ioctl_free_segments(struct the_nilfs *nilfs, + struct nilfs_argv *argv, void *buf) { + size_t nmembs = argv->v_nmembs; struct nilfs_sb_info *sbi = nilfs->ns_writer; int ret; @@ -481,31 +450,19 @@ nilfs_ioctl_do_free_segments(struct the_nilfs *nilfs, __u64 *posp, int flags, return (ret < 0) ? ret : nmembs; } -static inline int nilfs_ioctl_free_segments(struct the_nilfs *nilfs, - struct nilfs_argv *argv, - int dir) -{ - return nilfs_ioctl_wrap_copy(nilfs, argv, dir, - nilfs_ioctl_do_free_segments); -} - int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs, - void __user *argp) + struct nilfs_argv *argv, void **kbufs) { - struct nilfs_argv argv[5]; const char *msg; - int dir, ret; - - if (copy_from_user(argv, argp, sizeof(argv))) - return -EFAULT; + int ret; - dir = _IOC_WRITE; - ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], dir); + ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], kbufs[0]); if (ret < 0) { msg = "cannot read source blocks"; goto failed; } - ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], dir); + + ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], kbufs[1]); if (ret < 0) { /* * can safely abort because checkpoints can be removed @@ -514,7 +471,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs, msg = "cannot delete checkpoints"; goto failed; } - ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], dir); + ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], kbufs[2]); if (ret < 0) { /* * can safely abort because DAT file is updated atomically @@ -523,7 +480,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs, msg = "cannot delete virtual blocks from DAT file"; goto failed; } - ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], dir); + ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], kbufs[3]); if (ret < 0) { /* * can safely abort because the operation is nondestructive. @@ -531,7 +488,7 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs, msg = "cannot mark copying blocks dirty"; goto failed; } - ret = nilfs_ioctl_free_segments(nilfs, &argv[4], dir); + ret = nilfs_ioctl_free_segments(nilfs, &argv[4], kbufs[4]); if (ret < 0) { /* * can safely abort because this operation is atomic. @@ -551,9 +508,75 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs, static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp, unsigned int cmd, void __user *argp) { + struct nilfs_argv argv[5]; + const static size_t argsz[5] = { + sizeof(struct nilfs_vdesc), + sizeof(struct nilfs_period), + sizeof(__u64), + sizeof(struct nilfs_bdesc), + sizeof(__u64), + }; + void __user *base; + void *kbufs[5]; + struct the_nilfs *nilfs; + size_t len, nsegs; + int n, ret; + if (!capable(CAP_SYS_ADMIN)) return -EPERM; - return nilfs_clean_segments(inode->i_sb, argp); + + if (copy_from_user(argv, argp, sizeof(argv))) + return -EFAULT; + + nsegs = argv[4].v_nmembs; + if (argv[4].v_size != argsz[4]) + return -EINVAL; + /* + * argv[4] points to segment numbers this ioctl cleans. We + * use kmalloc() for its buffer because memory used for the + * segment numbers is enough small. + */ + kbufs[4] = memdup_user((void __user *)(unsigned long)argv[4].v_base, + nsegs * sizeof(__u64)); + if (IS_ERR(kbufs[4])) + return PTR_ERR(kbufs[4]); + + nilfs = NILFS_SB(inode->i_sb)->s_nilfs; + + for (n = 0; n < 4; n++) { + ret = -EINVAL; + if (argv[n].v_size != argsz[n]) + goto out_free; + + if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment) + goto out_free; + + len = argv[n].v_size * argv[n].v_nmembs; + base = (void __user *)(unsigned long)argv[n].v_base; + if (len == 0) { + kbufs[n] = NULL; + continue; + } + + kbufs[n] = vmalloc(len); + if (!kbufs[n]) { + ret = -ENOMEM; + goto out_free; + } + if (copy_from_user(kbufs[n], base, len)) { + ret = -EFAULT; + vfree(kbufs[n]); + goto out_free; + } + } + + ret = nilfs_clean_segments(inode->i_sb, argv, kbufs); + + out_free: + while (--n > 0) + vfree(kbufs[n]); + kfree(kbufs[4]); + return ret; } static int nilfs_ioctl_sync(struct inode *inode, struct file *filp, diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h index 3d0c18a..da6fc0b 100644 --- a/fs/nilfs2/nilfs.h +++ b/fs/nilfs2/nilfs.h @@ -236,7 +236,8 @@ extern int nilfs_sync_file(struct file *, struct dentry *, int); /* ioctl.c */ long nilfs_ioctl(struct file *, unsigned int, unsigned long); -int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, void __user *); +int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, struct nilfs_argv *, + void **); /* inode.c */ extern struct inode *nilfs_new_inode(struct inode *, int); diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c index fb70ec3..22c7f65 100644 --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -2589,7 +2589,8 @@ nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head) } } -int nilfs_clean_segments(struct super_block *sb, void __user *argp) +int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv, + void **kbufs) { struct nilfs_sb_info *sbi = NILFS_SB(sb); struct nilfs_sc_info *sci = NILFS_SC(sbi); @@ -2606,7 +2607,7 @@ int nilfs_clean_segments(struct super_block *sb, void __user *argp) err = nilfs_init_gcdat_inode(nilfs); if (unlikely(err)) goto out_unlock; - err = nilfs_ioctl_prepare_clean_segments(nilfs, argp); + err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs); if (unlikely(err)) goto out_unlock; diff --git a/fs/nilfs2/segment.h b/fs/nilfs2/segment.h index a98fc1e..476bdd5 100644 --- a/fs/nilfs2/segment.h +++ b/fs/nilfs2/segment.h @@ -222,7 +222,8 @@ extern int nilfs_construct_segment(struct super_block *); extern int nilfs_construct_dsync_segment(struct super_block *, struct inode *, loff_t, loff_t); extern void nilfs_flush_segment(struct super_block *, ino_t); -extern int nilfs_clean_segments(struct super_block *, void __user *); +extern int nilfs_clean_segments(struct super_block *, struct nilfs_argv *, + void **); extern int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *, __u64 *, size_t); -- 1.8.2.3