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authorDan Williams <dan.j.williams@intel.com>2017-04-07 09:47:24 -0700
committerDan Williams <dan.j.williams@intel.com>2017-04-10 17:21:45 -0700
commit0beb2012a1722633515c8aaa263c73449636c893 (patch)
treeedc1f13214fc24f53e333185e59d24c54a6b9b6a /drivers/nvdimm/bus.c
parentfe514739d8538783749d3ce72f78e5a999ea5668 (diff)
libnvdimm: fix reconfig_mutex, mmap_sem, and jbd2_handle lockdep splat
Holding the reconfig_mutex over a potential userspace fault sets up a lockdep dependency chain between filesystem-DAX and the libnvdimm ioctl path. Move the user access outside of the lock. [ INFO: possible circular locking dependency detected ] 4.11.0-rc3+ #13 Tainted: G W O ------------------------------------------------------- fallocate/16656 is trying to acquire lock: (&nvdimm_bus->reconfig_mutex){+.+.+.}, at: [<ffffffffa00080b1>] nvdimm_bus_lock+0x21/0x30 [libnvdimm] but task is already holding lock: (jbd2_handle){++++..}, at: [<ffffffff813b4944>] start_this_handle+0x104/0x460 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (jbd2_handle){++++..}: lock_acquire+0xbd/0x200 start_this_handle+0x16a/0x460 jbd2__journal_start+0xe9/0x2d0 __ext4_journal_start_sb+0x89/0x1c0 ext4_dirty_inode+0x32/0x70 __mark_inode_dirty+0x235/0x670 generic_update_time+0x87/0xd0 touch_atime+0xa9/0xd0 ext4_file_mmap+0x90/0xb0 mmap_region+0x370/0x5b0 do_mmap+0x415/0x4f0 vm_mmap_pgoff+0xd7/0x120 SyS_mmap_pgoff+0x1c5/0x290 SyS_mmap+0x22/0x30 entry_SYSCALL_64_fastpath+0x1f/0xc2 -> #1 (&mm->mmap_sem){++++++}: lock_acquire+0xbd/0x200 __might_fault+0x70/0xa0 __nd_ioctl+0x683/0x720 [libnvdimm] nvdimm_ioctl+0x8b/0xe0 [libnvdimm] do_vfs_ioctl+0xa8/0x740 SyS_ioctl+0x79/0x90 do_syscall_64+0x6c/0x200 return_from_SYSCALL_64+0x0/0x7a -> #0 (&nvdimm_bus->reconfig_mutex){+.+.+.}: __lock_acquire+0x16b6/0x1730 lock_acquire+0xbd/0x200 __mutex_lock+0x88/0x9b0 mutex_lock_nested+0x1b/0x20 nvdimm_bus_lock+0x21/0x30 [libnvdimm] nvdimm_forget_poison+0x25/0x50 [libnvdimm] nvdimm_clear_poison+0x106/0x140 [libnvdimm] pmem_do_bvec+0x1c2/0x2b0 [nd_pmem] pmem_make_request+0xf9/0x270 [nd_pmem] generic_make_request+0x118/0x3b0 submit_bio+0x75/0x150 Cc: <stable@vger.kernel.org> Fixes: 62232e45f4a2 ("libnvdimm: control (ioctl) messages for nvdimm_bus and nvdimm devices") Cc: Dave Jiang <dave.jiang@intel.com> Reported-by: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/bus.c')
-rw-r--r--drivers/nvdimm/bus.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 23d4a1728cdf..351bac8f6503 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -934,8 +934,14 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
rc = nd_desc->ndctl(nd_desc, nvdimm, cmd, buf, buf_len, NULL);
if (rc < 0)
goto out_unlock;
+ nvdimm_bus_unlock(&nvdimm_bus->dev);
+
if (copy_to_user(p, buf, buf_len))
rc = -EFAULT;
+
+ vfree(buf);
+ return rc;
+
out_unlock:
nvdimm_bus_unlock(&nvdimm_bus->dev);
out: