On 09/06/2017 08:45 PM, lixiubo@xxxxxxxxxxxxxxxxxxxx wrote:
> From: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
>
> Before the nl REMOVE msg has been sent to the userspace, the ring's
> and other resources have been released, but the userspace maybe still
> using them. And then we can see the crash messages like:
>
> ring broken, not handling completions
> BUG: unable to handle kernel paging request at ffffffffffffffd0
> IP: tcmu_handle_completions+0x134/0x2f0 [target_core_user]
> PGD 11bdc0c067
> P4D 11bdc0c067
> PUD 11bdc0e067
> PMD 0
>
> Oops: 0000 [#1] SMP
> cmd_id not found, ring is broken
> RIP: 0010:tcmu_handle_completions+0x134/0x2f0 [target_core_user]
> RSP: 0018:ffffb8a2d8983d88 EFLAGS: 00010296
> RAX: 0000000000000000 RBX: ffffb8a2aaa4e000 RCX: 00000000ffffffff
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000220
> R10: 0000000076c71401 R11: ffff8d2e76c713f0 R12: ffffb8a2aad56bc0
> R13: 000000000000001c R14: ffff8d2e32c90000 R15: ffff8d2e76c713f0
> FS: 00007f411ffff700(0000) GS:ffff8d1e7fdc0000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffd0 CR3: 0000001027070000 CR4:
> 00000000001406e0
> Call Trace:
> ? tcmu_irqcontrol+0x2a/0x40 [target_core_user]
> ? uio_write+0x7b/0xc0 [uio]
> ? __vfs_write+0x37/0x150
> ? __getnstimeofday64+0x3b/0xd0
> ? vfs_write+0xb2/0x1b0
> ? syscall_trace_enter+0x1d0/0x2b0
> ? SyS_write+0x55/0xc0
> ? do_syscall_64+0x67/0x150
> ? entry_SYSCALL64_slow_path+0x25/0x25
> Code: 41 5d 41 5e 41 5f 5d c3 83 f8 01 0f 85 cf 01 00
> 00 48 8b 7d d0 e8 dd 5c 1d f3 41 0f b7 74 24 04 48 8b
> 7d c8 31 d2 e8 5c c7 1b f3 <48> 8b 7d d0 49 89 c7 c6 07
> 00 0f 1f 40 00 4d 85 ff 0f 84 82 01 RIP:
> tcmu_handle_completions+0x134/0x2f0 [target_core_user]
> RSP: ffffb8a2d8983d88
> CR2: ffffffffffffffd0
>
> And the crash also could happen in tcmu_page_fault and other places.
>
> Signed-off-by: Zhang Zhuoyu <zhangzhuoyu@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_user.c | 86 +++++++++++++++++++--------------------
> 1 file changed, 43 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
> index 942d0942..3336b00 100644
> --- a/drivers/target/target_core_user.c
> +++ b/drivers/target/target_core_user.c
> @@ -1280,10 +1280,53 @@ static void tcmu_dev_call_rcu(struct rcu_head *p)
> kfree(udev);
> }
>
> +static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd)
> +{
> + if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) {
> + kmem_cache_free(tcmu_cmd_cache, cmd);
> + return 0;
> + }
> + return -EINVAL;
> +}
> +
> +static void tcmu_blocks_release(struct tcmu_dev *udev)
> +{
> + int i;
> + struct page *page;
> +
> + /* Try to release all block pages */
> + mutex_lock(&udev->cmdr_lock);
> + for (i = 0; i <= udev->dbi_max; i++) {
> + page = radix_tree_delete(&udev->data_blocks, i);
> + if (page) {
> + __free_page(page);
> + atomic_dec(&global_db_count);
> + }
> + }
> + mutex_unlock(&udev->cmdr_lock);
> +}
> +
> static void tcmu_dev_kref_release(struct kref *kref)
> {
> struct tcmu_dev *udev = container_of(kref, struct tcmu_dev, kref);
> struct se_device *dev = &udev->se_dev;
> + struct tcmu_cmd *cmd;
> + bool all_expired = true;
> + int i;
> +
> + vfree(udev->mb_addr);
> +
> + /* Upper layer should drain all requests before calling this */
> + spin_lock_irq(&udev->commands_lock);
> + idr_for_each_entry(&udev->commands, cmd, i) {
> + if (tcmu_check_and_free_pending_cmd(cmd) != 0)
> + all_expired = false;
> + }
> + idr_destroy(&udev->commands);
> + spin_unlock_irq(&udev->commands_lock);
> + WARN_ON(!all_expired);
> +
> + tcmu_blocks_release(udev);
I think we also want to move the INIT_RADIX_TREE to tcmu_alloc_device.
We do not do INIT_RADIX_TREE until tcmu_configure_device and that
function might fail before the INIT call or configure might not even be
called. Right now, all the INIT does is set the rnode to NULL and the
gfp mask, so we would be ok, but if they change what happens then we
will hit problems.
>
> call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
> }
> @@ -1534,37 +1577,11 @@ static int tcmu_configure_device(struct se_device *dev)
> return ret;
> }
>
> -static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd)
> -{
> - if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) {
> - kmem_cache_free(tcmu_cmd_cache, cmd);
> - return 0;
> - }
> - return -EINVAL;
> -}
> -
> static bool tcmu_dev_configured(struct tcmu_dev *udev)
> {
> return udev->uio_info.uio_dev ? true : false;
> }
>
> -static void tcmu_blocks_release(struct tcmu_dev *udev)
> -{
> - int i;
> - struct page *page;
> -
> - /* Try to release all block pages */
> - mutex_lock(&udev->cmdr_lock);
> - for (i = 0; i <= udev->dbi_max; i++) {
> - page = radix_tree_delete(&udev->data_blocks, i);
> - if (page) {
> - __free_page(page);
> - atomic_dec(&global_db_count);
> - }
> - }
> - mutex_unlock(&udev->cmdr_lock);
> -}
> -
> static void tcmu_free_device(struct se_device *dev)
> {
> struct tcmu_dev *udev = TCMU_DEV(dev);
> @@ -1576,9 +1593,6 @@ static void tcmu_free_device(struct se_device *dev)
> static void tcmu_destroy_device(struct se_device *dev)
> {
> struct tcmu_dev *udev = TCMU_DEV(dev);
> - struct tcmu_cmd *cmd;
> - bool all_expired = true;
> - int i;
>
> del_timer_sync(&udev->timeout);
>
> @@ -1586,20 +1600,6 @@ static void tcmu_destroy_device(struct se_device *dev)
> list_del(&udev->node);
> mutex_unlock(&root_udev_mutex);
>
> - vfree(udev->mb_addr);
> -
> - /* Upper layer should drain all requests before calling this */
> - spin_lock_irq(&udev->commands_lock);
> - idr_for_each_entry(&udev->commands, cmd, i) {
> - if (tcmu_check_and_free_pending_cmd(cmd) != 0)
> - all_expired = false;
> - }
> - idr_destroy(&udev->commands);
> - spin_unlock_irq(&udev->commands_lock);
> - WARN_ON(!all_expired);
> -
> - tcmu_blocks_release(udev);
> -
> tcmu_netlink_event(udev, TCMU_CMD_REMOVED_DEVICE, 0, NULL);
>
> uio_unregister_device(&udev->uio_info);
>
--
To unsubscribe from this list: send the line "unsubscribe target-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
