From 60aaf933854511630e16be4efe0f96485e132de4 Mon Sep 17 00:00:00 2001 From: majianpeng Date: Thu, 14 Nov 2013 15:16:20 +1100 Subject: md/raid5: Use conf->device_lock protect changing of multi-thread resources. When we change group_thread_cnt from sysfs entry, it can OOPS. The kernel messages are: [ 135.299021] BUG: unable to handle kernel NULL pointer dereference at (null) [ 135.299073] IP: [] handle_active_stripes+0x32b/0x440 [ 135.299107] PGD 0 [ 135.299122] Oops: 0000 [#1] SMP [ 135.299144] Modules linked in: netconsole e1000e ptp pps_core [ 135.299188] CPU: 3 PID: 2225 Comm: md0_raid5 Not tainted 3.12.0+ #24 [ 135.299214] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS 080015 11/09/2011 [ 135.299255] task: ffff8800b9638f80 ti: ffff8800b77a4000 task.ti: ffff8800b77a4000 [ 135.299283] RIP: 0010:[] [] handle_active_stripes+0x32b/0x440 [ 135.299323] RSP: 0018:ffff8800b77a5c48 EFLAGS: 00010002 [ 135.299344] RAX: ffff880037bb5c70 RBX: 0000000000000000 RCX: 0000000000000008 [ 135.299371] RDX: ffff880037bb5cb8 RSI: 0000000000000001 RDI: ffff880037bb5c00 [ 135.299398] RBP: ffff8800b77a5d08 R08: 0000000000000001 R09: 0000000000000000 [ 135.299425] R10: ffff8800b77a5c98 R11: 00000000ffffffff R12: ffff880037bb5c00 [ 135.299452] R13: 0000000000000000 R14: 0000000000000000 R15: ffff880037bb5c70 [ 135.299479] FS: 0000000000000000(0000) GS:ffff88013fd80000(0000) knlGS:0000000000000000 [ 135.299510] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 135.299532] CR2: 0000000000000000 CR3: 0000000001c0b000 CR4: 00000000000407e0 [ 135.299559] Stack: [ 135.299570] ffff8800b77a5c88 ffffffff8107383e ffff8800b77a5c88 ffff880037a64300 [ 135.299611] 000000000000ec08 ffff880037bb5cb8 ffff8800b77a5c98 ffffffffffffffd8 [ 135.299654] 000000000000ec08 ffff880037bb5c60 ffff8800b77a5c98 ffff8800b77a5c98 [ 135.299696] Call Trace: [ 135.299711] [] ? __wake_up+0x4e/0x70 [ 135.299733] [] raid5d+0x4c8/0x680 [ 135.299756] [] ? schedule_timeout+0x15d/0x1f0 [ 135.299781] [] md_thread+0x11f/0x170 [ 135.299804] [] ? wake_up_bit+0x40/0x40 [ 135.299826] [] ? md_rdev_init+0x110/0x110 [ 135.299850] [] kthread+0xc6/0xd0 [ 135.299871] [] ? kthread_freezable_should_stop+0x70/0x70 [ 135.299899] [] ret_from_fork+0x7c/0xb0 [ 135.299923] [] ? kthread_freezable_should_stop+0x70/0x70 [ 135.299951] Code: ff ff ff 0f 84 d7 fe ff ff e9 5c fe ff ff 66 90 41 8b b4 24 d8 01 00 00 45 31 ed 85 f6 0f 8e 7b fd ff ff 49 8b 9c 24 d0 01 00 00 <48> 3b 1b 49 89 dd 0f 85 67 fd ff ff 48 8d 43 28 31 d2 eb 17 90 [ 135.300005] RIP [] handle_active_stripes+0x32b/0x440 [ 135.300005] RSP [ 135.300005] CR2: 0000000000000000 [ 135.300005] ---[ end trace 504854e5bb7562ed ]--- [ 135.300005] Kernel panic - not syncing: Fatal exception This is because raid5d() can be running when the multi-thread resources are changed via system. We see need to provide locking. mddev->device_lock is suitable, but we cannot simple call alloc_thread_groups under this lock as we cannot allocate memory while holding a spinlock. So change alloc_thread_groups() to allocate and return the data structures, then raid5_store_group_thread_cnt() can take the lock while updating the pointers to the data structures. This fixes a bug introduced in 3.12 and so is suitable for the 3.12.x stable series. Fixes: b721420e8719131896b009b11edbbd27 Cc: stable@vger.kernel.org (3.12) Signed-off-by: Jianpeng Ma Signed-off-by: NeilBrown Reviewed-by: Shaohua Li --- drivers/md/raid5.c | 63 +++++++++++++++++++++++++++++++++--------------------- 1 file changed, 39 insertions(+), 24 deletions(-) (limited to 'drivers') diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index fea67727f807..c7db410190c4 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5387,15 +5387,18 @@ raid5_show_group_thread_cnt(struct mddev *mddev, char *page) return 0; } -static int alloc_thread_groups(struct r5conf *conf, int cnt); +static int alloc_thread_groups(struct r5conf *conf, int cnt, + int *group_cnt, + int *worker_cnt_per_group, + struct r5worker_group **worker_groups); static ssize_t raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len) { struct r5conf *conf = mddev->private; unsigned long new; int err; - struct r5worker_group *old_groups; - int old_group_cnt; + struct r5worker_group *new_groups, *old_groups; + int group_cnt, worker_cnt_per_group; if (len >= PAGE_SIZE) return -EINVAL; @@ -5411,17 +5414,19 @@ raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len) mddev_suspend(mddev); old_groups = conf->worker_groups; - old_group_cnt = conf->worker_cnt_per_group; - if (old_groups) flush_workqueue(raid5_wq); - conf->worker_groups = NULL; - err = alloc_thread_groups(conf, new); - if (err) { - conf->worker_groups = old_groups; - conf->worker_cnt_per_group = old_group_cnt; - } else { + err = alloc_thread_groups(conf, new, + &group_cnt, &worker_cnt_per_group, + &new_groups); + if (!err) { + spin_lock_irq(&conf->device_lock); + conf->group_cnt = group_cnt; + conf->worker_cnt_per_group = worker_cnt_per_group; + conf->worker_groups = new_groups; + spin_unlock_irq(&conf->device_lock); + if (old_groups) kfree(old_groups[0].workers); kfree(old_groups); @@ -5451,33 +5456,36 @@ static struct attribute_group raid5_attrs_group = { .attrs = raid5_attrs, }; -static int alloc_thread_groups(struct r5conf *conf, int cnt) +static int alloc_thread_groups(struct r5conf *conf, int cnt, + int *group_cnt, + int *worker_cnt_per_group, + struct r5worker_group **worker_groups) { int i, j, k; ssize_t size; struct r5worker *workers; - conf->worker_cnt_per_group = cnt; + *worker_cnt_per_group = cnt; if (cnt == 0) { - conf->worker_groups = NULL; + *group_cnt = 0; + *worker_groups = NULL; return 0; } - conf->group_cnt = num_possible_nodes(); + *group_cnt = num_possible_nodes(); size = sizeof(struct r5worker) * cnt; - workers = kzalloc(size * conf->group_cnt, GFP_NOIO); - conf->worker_groups = kzalloc(sizeof(struct r5worker_group) * - conf->group_cnt, GFP_NOIO); - if (!conf->worker_groups || !workers) { + workers = kzalloc(size * *group_cnt, GFP_NOIO); + *worker_groups = kzalloc(sizeof(struct r5worker_group) * + *group_cnt, GFP_NOIO); + if (!*worker_groups || !workers) { kfree(workers); - kfree(conf->worker_groups); - conf->worker_groups = NULL; + kfree(*worker_groups); return -ENOMEM; } - for (i = 0; i < conf->group_cnt; i++) { + for (i = 0; i < *group_cnt; i++) { struct r5worker_group *group; - group = &conf->worker_groups[i]; + group = worker_groups[i]; INIT_LIST_HEAD(&group->handle_list); group->conf = conf; group->workers = workers + i * cnt; @@ -5640,6 +5648,8 @@ static struct r5conf *setup_conf(struct mddev *mddev) struct disk_info *disk; char pers_name[6]; int i; + int group_cnt, worker_cnt_per_group; + struct r5worker_group *new_group; if (mddev->new_level != 5 && mddev->new_level != 4 @@ -5674,7 +5684,12 @@ static struct r5conf *setup_conf(struct mddev *mddev) if (conf == NULL) goto abort; /* Don't enable multi-threading by default*/ - if (alloc_thread_groups(conf, 0)) + if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group, + &new_group)) { + conf->group_cnt = group_cnt; + conf->worker_cnt_per_group = worker_cnt_per_group; + conf->worker_groups = new_group; + } else goto abort; spin_lock_init(&conf->device_lock); seqcount_init(&conf->gen_lock); -- cgit v1.2.3