On 05/02, Chao Yu wrote: > On 2018/4/28 10:36, Jaegeuk Kim wrote: > > 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). > > How about below cases? > > - do_remount
Was there no guard to block any filesystem operations? If it's true, yeah, we need to cover them. > - do_remount_sb > - remount_fs > - f2fs_remount > - stop_gc_thread > - fsync > - f2fs_sync_file > - file_write_and_wait_range > - f2fs_write_data_pages > - __write_data_page > - should_update_inplace > - check_inplace_update_policy > - need_SSR > : sbi->gc_thread = NULL; > > or > > - write_data_page > - allocate_data_block > - allocate_segment > - get_ssr_segment > - select_gc_type > : sbi->gc_thread = NULL; > > Thanks, > > > > >> > >> 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
