On 04/18, 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
Do we simply need a lock for this? > > 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. > > In order to fix this issue, keep gc_thread structure valid in sbi all > the time instead of alloc/free it dynamically. > > Signed-off-by: Chao Yu <yuch...@huawei.com> > --- > fs/f2fs/debug.c | 3 +-- > fs/f2fs/f2fs.h | 7 +++++++ > fs/f2fs/gc.c | 58 > +++++++++++++++++++++++++++++++++---------------------- > fs/f2fs/segment.c | 4 ++-- > fs/f2fs/super.c | 13 +++++++++++-- > fs/f2fs/sysfs.c | 8 ++++---- > 6 files changed, 60 insertions(+), 33 deletions(-) > > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c > index 715beb85e9db..7bb036a3bb81 100644 > --- a/fs/f2fs/debug.c > +++ b/fs/f2fs/debug.c > @@ -223,8 +223,7 @@ 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 567c6bb57ae3..c553f63199e8 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); > @@ -2954,6 +2959,8 @@ 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); > block_t start_bidx_of_node(unsigned int node_ofs, struct inode *inode); > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > index da89ca16a55d..7d310e454b77 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; > @@ -139,26 +137,41 @@ int start_gc_thread(struct f2fs_sb_info *sbi) > gc_th->atomic_file[FG_GC] = 0; > > 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) > { > - 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); > + > + if (gc_th->f2fs_gc_task) { > + kthread_stop(gc_th->f2fs_gc_task); > + gc_th->f2fs_gc_task = NULL; > + } > } > > static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type) > @@ -190,15 +203,14 @@ 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) && > + if (gc_type != FG_GC && !GC_I(sbi)->gc_urgent && > p->max_search > sbi->max_victim_search) > p->max_search = sbi->max_victim_search; > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 831cefa088bc..c869ce54be4d 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -177,7 +177,7 @@ bool need_SSR(struct f2fs_sb_info *sbi) > > if (test_opt(sbi, LFS)) > return false; > - if (sbi->gc_thread && sbi->gc_thread->gc_urgent) > + if (GC_I(sbi)->gc_urgent) > return true; > > return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs + > @@ -1422,7 +1422,7 @@ static int issue_discard_thread(void *data) > if (dcc->discard_wake) > dcc->discard_wake = 0; > > - if (sbi->gc_thread && sbi->gc_thread->gc_urgent) > + if (GC_I(sbi)->gc_urgent) > init_discard_policy(&dpolicy, DPOLICY_FORCE, 1); > > sb_start_intwrite(sbi->sb); > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index d01c11f5e9c1..f3a5f463496f 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -1012,6 +1012,8 @@ static void f2fs_put_super(struct super_block *sb) > write_checkpoint(sbi, &cpc); > } > > + destroy_gc_context(sbi); > + > /* write_checkpoint can update stat informaion */ > f2fs_destroy_stats(sbi); > > @@ -1044,6 +1046,7 @@ 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++) > @@ -1476,11 +1479,11 @@ 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) { > + if (GC_I(sbi)->f2fs_gc_task) { > stop_gc_thread(sbi); > need_restart_gc = true; > } > - } else if (!sbi->gc_thread) { > + } else if (!GC_I(sbi)->f2fs_gc_task) { > err = start_gc_thread(sbi); > if (err) > goto restore_opts; > @@ -2771,6 +2774,10 @@ 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 +2988,8 @@ 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..fb3cd477d985 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) > @@ -252,9 +252,9 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, > > if (!strcmp(a->attr.name, "iostat_enable") && *ui == 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 (!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); > } > > -- > 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 Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel