On 04/27, Chao Yu wrote: > On 2018/4/27 0:03, Jaegeuk Kim wrote: > > On 04/24, Chao Yu wrote: > >> Thread A Thread B Thread C > >> - f2fs_remount > >> - stop_gc_thread > >> - f2fs_sbi_store > >> - issue_discard_thread > >> sbi->gc_thread = NULL; > >> sbi->gc_thread->gc_wake = 1 > >> access > >> sbi->gc_thread->gc_urgent > >> > >> Previously, we allocate memory for sbi->gc_thread based on background > >> gc thread mount option, the memory can be released if we turn off > >> that mount option, but still there are several places access gc_thread > >> pointer without considering race condition, result in NULL point > >> dereference. > > > > Do we just need to check &sb->s_umount in f2fs_sbi_store() and > > Better, > > > issue_discard_thread? > > There is more cases can be called from different scenarios: > - select_policy() > - need_SSR()
No? They should be blocked by remount(2). > > Thanks, > > > > >> > >> In order to fix this issue, keep gc_thread structure valid in sbi all > >> the time instead of alloc/free it dynamically. > >> > >> In addition, add a rw semaphore to exclude rw operation in fields of > >> gc_thread. > >> > >> Signed-off-by: Chao Yu <[email protected]> > >> --- > >> v2: > >> - add a rw semaphore to exclude rw operation suggested by Jaegeuk. > >> fs/f2fs/debug.c | 3 +-- > >> fs/f2fs/f2fs.h | 9 ++++++- > >> fs/f2fs/gc.c | 78 > >> ++++++++++++++++++++++++++++++++++++------------------- > >> fs/f2fs/gc.h | 1 + > >> fs/f2fs/segment.c | 10 +++++-- > >> fs/f2fs/super.c | 26 +++++++++++++------ > >> fs/f2fs/sysfs.c | 26 ++++++++++++++----- > >> 7 files changed, 107 insertions(+), 46 deletions(-) > >> > >> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c > >> index a66107b5cfff..0fbd674c66fb 100644 > >> --- a/fs/f2fs/debug.c > >> +++ b/fs/f2fs/debug.c > >> @@ -221,8 +221,7 @@ static void update_mem_info(struct f2fs_sb_info *sbi) > >> si->cache_mem = 0; > >> > >> /* build gc */ > >> - if (sbi->gc_thread) > >> - si->cache_mem += sizeof(struct f2fs_gc_kthread); > >> + si->cache_mem += sizeof(struct f2fs_gc_kthread); > >> > >> /* build merge flush thread */ > >> if (SM_I(sbi)->fcc_info) > >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > >> index 8f3ad9662d13..75d3b4875429 100644 > >> --- a/fs/f2fs/f2fs.h > >> +++ b/fs/f2fs/f2fs.h > >> @@ -1412,6 +1412,11 @@ static inline struct sit_info *SIT_I(struct > >> f2fs_sb_info *sbi) > >> return (struct sit_info *)(SM_I(sbi)->sit_info); > >> } > >> > >> +static inline struct f2fs_gc_kthread *GC_I(struct f2fs_sb_info *sbi) > >> +{ > >> + return (struct f2fs_gc_kthread *)(sbi->gc_thread); > >> +} > >> + > >> static inline struct free_segmap_info *FREE_I(struct f2fs_sb_info *sbi) > >> { > >> return (struct free_segmap_info *)(SM_I(sbi)->free_info); > >> @@ -2954,8 +2959,10 @@ bool f2fs_overwrite_io(struct inode *inode, loff_t > >> pos, size_t len); > >> /* > >> * gc.c > >> */ > >> +int init_gc_context(struct f2fs_sb_info *sbi); > >> +void destroy_gc_context(struct f2fs_sb_info * sbi); > >> int start_gc_thread(struct f2fs_sb_info *sbi); > >> -void stop_gc_thread(struct f2fs_sb_info *sbi); > >> +bool stop_gc_thread(struct f2fs_sb_info *sbi); > >> block_t start_bidx_of_node(unsigned int node_ofs, struct inode *inode); > >> int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, bool background, > >> unsigned int segno); > >> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > >> index 70418b34c5f6..2febb84b2fd6 100644 > >> --- a/fs/f2fs/gc.c > >> +++ b/fs/f2fs/gc.c > >> @@ -26,8 +26,8 @@ > >> static int gc_thread_func(void *data) > >> { > >> struct f2fs_sb_info *sbi = data; > >> - struct f2fs_gc_kthread *gc_th = sbi->gc_thread; > >> - wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head; > >> + struct f2fs_gc_kthread *gc_th = GC_I(sbi); > >> + wait_queue_head_t *wq = &gc_th->gc_wait_queue_head; > >> unsigned int wait_ms; > >> > >> wait_ms = gc_th->min_sleep_time; > >> @@ -114,17 +114,15 @@ static int gc_thread_func(void *data) > >> return 0; > >> } > >> > >> -int start_gc_thread(struct f2fs_sb_info *sbi) > >> +int init_gc_context(struct f2fs_sb_info *sbi) > >> { > >> struct f2fs_gc_kthread *gc_th; > >> - dev_t dev = sbi->sb->s_bdev->bd_dev; > >> - int err = 0; > >> > >> gc_th = f2fs_kmalloc(sbi, sizeof(struct f2fs_gc_kthread), GFP_KERNEL); > >> - if (!gc_th) { > >> - err = -ENOMEM; > >> - goto out; > >> - } > >> + if (!gc_th) > >> + return -ENOMEM; > >> + > >> + gc_th->f2fs_gc_task = NULL; > >> > >> gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME; > >> gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME; > >> @@ -135,35 +133,59 @@ int start_gc_thread(struct f2fs_sb_info *sbi) > >> gc_th->gc_urgent = 0; > >> gc_th->gc_wake= 0; > >> > >> + init_rwsem(&gc_th->gc_rwsem); > >> + > >> sbi->gc_thread = gc_th; > >> - init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head); > >> - sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi, > >> + > >> + return 0; > >> +} > >> + > >> +void destroy_gc_context(struct f2fs_sb_info *sbi) > >> +{ > >> + kfree(GC_I(sbi)); > >> + sbi->gc_thread = NULL; > >> +} > >> + > >> +int start_gc_thread(struct f2fs_sb_info *sbi) > >> +{ > >> + struct f2fs_gc_kthread *gc_th = GC_I(sbi); > >> + dev_t dev = sbi->sb->s_bdev->bd_dev; > >> + int err = 0; > >> + > >> + init_waitqueue_head(&gc_th->gc_wait_queue_head); > >> + gc_th->f2fs_gc_task = kthread_run(gc_thread_func, sbi, > >> "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev)); > >> if (IS_ERR(gc_th->f2fs_gc_task)) { > >> err = PTR_ERR(gc_th->f2fs_gc_task); > >> - kfree(gc_th); > >> - sbi->gc_thread = NULL; > >> + gc_th->f2fs_gc_task = NULL; > >> } > >> -out: > >> + > >> return err; > >> } > >> > >> -void stop_gc_thread(struct f2fs_sb_info *sbi) > >> +bool stop_gc_thread(struct f2fs_sb_info *sbi) > >> { > >> - struct f2fs_gc_kthread *gc_th = sbi->gc_thread; > >> - if (!gc_th) > >> - return; > >> - kthread_stop(gc_th->f2fs_gc_task); > >> - kfree(gc_th); > >> - sbi->gc_thread = NULL; > >> + struct f2fs_gc_kthread *gc_th = GC_I(sbi); > >> + bool stopped = false; > >> + > >> + down_write(&gc_th->gc_rwsem); > >> + if (gc_th->f2fs_gc_task) { > >> + kthread_stop(gc_th->f2fs_gc_task); > >> + gc_th->f2fs_gc_task = NULL; > >> + stopped = true; > >> + } > >> + up_write(&gc_th->gc_rwsem); > >> + > >> + return stopped; > >> } > >> > >> static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type) > >> { > >> int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY; > >> > >> - if (!gc_th) > >> - return gc_mode; > >> + down_read(&gc_th->gc_rwsem); > >> + if (!gc_th->f2fs_gc_task) > >> + goto out; > >> > >> if (gc_th->gc_idle) { > >> if (gc_th->gc_idle == 1) > >> @@ -173,6 +195,8 @@ static int select_gc_type(struct f2fs_gc_kthread > >> *gc_th, int gc_type) > >> } > >> if (gc_th->gc_urgent) > >> gc_mode = GC_GREEDY; > >> +out: > >> + up_read(&gc_th->gc_rwsem); > >> return gc_mode; > >> } > >> > >> @@ -187,17 +211,19 @@ static void select_policy(struct f2fs_sb_info *sbi, > >> int gc_type, > >> p->max_search = dirty_i->nr_dirty[type]; > >> p->ofs_unit = 1; > >> } else { > >> - p->gc_mode = select_gc_type(sbi->gc_thread, gc_type); > >> + p->gc_mode = select_gc_type(GC_I(sbi), gc_type); > >> p->dirty_segmap = dirty_i->dirty_segmap[DIRTY]; > >> p->max_search = dirty_i->nr_dirty[DIRTY]; > >> p->ofs_unit = sbi->segs_per_sec; > >> } > >> > >> /* we need to check every dirty segments in the FG_GC case */ > >> - if (gc_type != FG_GC && > >> - (sbi->gc_thread && !sbi->gc_thread->gc_urgent) && > >> + down_read(&GC_I(sbi)->gc_rwsem); > >> + if (gc_type != FG_GC && GC_I(sbi)->f2fs_gc_task && > >> + !GC_I(sbi)->gc_urgent && > >> p->max_search > sbi->max_victim_search) > >> p->max_search = sbi->max_victim_search; > >> + up_read(&GC_I(sbi)->gc_rwsem); > >> > >> /* let's select beginning hot/small space first in no_heap mode*/ > >> if (test_opt(sbi, NOHEAP) && > >> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h > >> index b0045d4c8d1e..9a5b273328c2 100644 > >> --- a/fs/f2fs/gc.h > >> +++ b/fs/f2fs/gc.h > >> @@ -26,6 +26,7 @@ > >> #define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */ > >> > >> struct f2fs_gc_kthread { > >> + struct rw_semaphore gc_rwsem; /* semaphore for f2fs_gc_task */ > >> struct task_struct *f2fs_gc_task; > >> wait_queue_head_t gc_wait_queue_head; > >> > >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > >> index 5960768d26df..f787eea1b2f6 100644 > >> --- a/fs/f2fs/segment.c > >> +++ b/fs/f2fs/segment.c > >> @@ -177,8 +177,12 @@ bool need_SSR(struct f2fs_sb_info *sbi) > >> > >> if (test_opt(sbi, LFS)) > >> return false; > >> - if (sbi->gc_thread && sbi->gc_thread->gc_urgent) > >> + down_read(&GC_I(sbi)->gc_rwsem); > >> + if (GC_I(sbi)->f2fs_gc_task && GC_I(sbi)->gc_urgent) { > >> + down_read(&GC_I(sbi)->gc_rwsem); > >> return true; > >> + } > >> + up_read(&GC_I(sbi)->gc_rwsem); > >> > >> return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs + > >> SM_I(sbi)->min_ssr_sections + reserved_sections(sbi)); > >> @@ -1425,8 +1429,10 @@ static int issue_discard_thread(void *data) > >> if (dcc->discard_wake) > >> dcc->discard_wake = 0; > >> > >> - if (sbi->gc_thread && sbi->gc_thread->gc_urgent) > >> + down_read(&GC_I(sbi)->gc_rwsem); > >> + if (GC_I(sbi)->f2fs_gc_task && GC_I(sbi)->gc_urgent) > >> init_discard_policy(&dpolicy, DPOLICY_FORCE, 1); > >> + up_read(&GC_I(sbi)->gc_rwsem); > >> > >> sb_start_intwrite(sbi->sb); > >> > >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > >> index dedb8e50b440..199f29dce86d 100644 > >> --- a/fs/f2fs/super.c > >> +++ b/fs/f2fs/super.c > >> @@ -1044,6 +1044,7 @@ static void f2fs_put_super(struct super_block *sb) > >> kfree(sbi->raw_super); > >> > >> destroy_device_list(sbi); > >> + destroy_gc_context(sbi); > >> mempool_destroy(sbi->write_io_dummy); > >> #ifdef CONFIG_QUOTA > >> for (i = 0; i < MAXQUOTAS; i++) > >> @@ -1476,15 +1477,18 @@ static int f2fs_remount(struct super_block *sb, > >> int *flags, char *data) > >> * option. Also sync the filesystem. > >> */ > >> if ((*flags & SB_RDONLY) || !test_opt(sbi, BG_GC)) { > >> - if (sbi->gc_thread) { > >> - stop_gc_thread(sbi); > >> - need_restart_gc = true; > >> + need_restart_gc = stop_gc_thread(sbi); > >> + } else { > >> + down_write(&GC_I(sbi)->gc_rwsem); > >> + if (!GC_I(sbi)->f2fs_gc_task) { > >> + err = start_gc_thread(sbi); > >> + if (err) { > >> + up_write(&GC_I(sbi)->gc_rwsem); > >> + goto restore_opts; > >> + } > >> + need_stop_gc = true; > >> } > >> - } else if (!sbi->gc_thread) { > >> - err = start_gc_thread(sbi); > >> - if (err) > >> - goto restore_opts; > >> - need_stop_gc = true; > >> + up_write(&GC_I(sbi)->gc_rwsem); > >> } > >> > >> if (*flags & SB_RDONLY || > >> @@ -2771,6 +2775,10 @@ static int f2fs_fill_super(struct super_block *sb, > >> void *data, int silent) > >> goto free_meta_inode; > >> } > >> > >> + err = init_gc_context(sbi); > >> + if (err) > >> + goto free_checkpoint; > >> + > >> /* Initialize device list */ > >> err = f2fs_scan_devices(sbi); > >> if (err) { > >> @@ -2981,6 +2989,8 @@ static int f2fs_fill_super(struct super_block *sb, > >> void *data, int silent) > >> destroy_segment_manager(sbi); > >> free_devices: > >> destroy_device_list(sbi); > >> + destroy_gc_context(sbi); > >> +free_checkpoint: > >> kfree(sbi->ckpt); > >> free_meta_inode: > >> make_bad_inode(sbi->meta_inode); > >> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > >> index 2c53de9251be..b8d09935e43f 100644 > >> --- a/fs/f2fs/sysfs.c > >> +++ b/fs/f2fs/sysfs.c > >> @@ -46,7 +46,7 @@ struct f2fs_attr { > >> static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int > >> struct_type) > >> { > >> if (struct_type == GC_THREAD) > >> - return (unsigned char *)sbi->gc_thread; > >> + return (unsigned char *)GC_I(sbi); > >> else if (struct_type == SM_INFO) > >> return (unsigned char *)SM_I(sbi); > >> else if (struct_type == DCC_INFO) > >> @@ -248,16 +248,28 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, > >> if (!strcmp(a->attr.name, "trim_sections")) > >> return -EINVAL; > >> > >> - *ui = t; > >> - > >> - if (!strcmp(a->attr.name, "iostat_enable") && *ui == 0) > >> + if (!strcmp(a->attr.name, "iostat_enable") && t == 0) > >> f2fs_reset_iostat(sbi); > >> - if (!strcmp(a->attr.name, "gc_urgent") && t == 1 && sbi->gc_thread) { > >> - sbi->gc_thread->gc_wake = 1; > >> - wake_up_interruptible_all(&sbi->gc_thread->gc_wait_queue_head); > >> + > >> + if (a->struct_type == GC_THREAD) { > >> + down_write(&GC_I(sbi)->gc_rwsem); > >> + if (!GC_I(sbi)->f2fs_gc_task) { > >> + up_write(&GC_I(sbi)->gc_rwsem); > >> + return -EINVAL; > >> + } > >> + } > >> + > >> + if (!strcmp(a->attr.name, "gc_urgent") && t == 1) { > >> + GC_I(sbi)->gc_wake = 1; > >> + wake_up_interruptible_all(&GC_I(sbi)->gc_wait_queue_head); > >> wake_up_discard_thread(sbi, true); > >> } > >> > >> + *ui = t; > >> + > >> + if (a->struct_type == GC_THREAD) > >> + up_write(&GC_I(sbi)->gc_rwsem); > >> + > >> return count; > >> } > >> > >> -- > >> 2.15.0.55.gc2ece9dc4de6 > > > > . > > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
