linux-stable.git/drivers/dax, branch linux-5.4.y

dax: make sure inodes are flushed before destroy cache

2022-04-15T12:18:12+00:00

[ Upstream commit a7e8de822e0b1979f08767c751f6c8a9c1d4ad86 ]

A bug can be triggered by following command

$ modprobe nd_pmem && modprobe -r nd_pmem

[   10.060014] BUG dax_cache (Not tainted): Objects remaining in dax_cache on __kmem_cache_shutdown()
[   10.060938] Slab 0x0000000085b729ac objects=9 used=1 fp=0x000000004f5ae469 flags=0x200000000010200(slab|head|node)
[   10.062433] Call Trace:
[   10.062673]  dump_stack_lvl+0x34/0x44
[   10.062865]  slab_err+0x90/0xd0
[   10.063619]  __kmem_cache_shutdown+0x13b/0x2f0
[   10.063848]  kmem_cache_destroy+0x4a/0x110
[   10.064058]  __x64_sys_delete_module+0x265/0x300

This is caused by dax_fs_exit() not flushing inodes before destroy cache.
To fix this issue, call rcu_barrier() before destroy cache.

Signed-off-by: Tong Zhang 
Reviewed-by: Ira Weiny 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20220212071111.148575-1-ztong0001@gmail.com
Fixes: 7b6be8444e0f ("dax: refactor dax-fs into a generic provider of 'struct dax_device' instances")
Signed-off-by: Dan Williams 
Signed-off-by: Sasha Levin

device-dax/core: Fix memory leak when rmmod dax.ko

2020-12-30T10:51:46+00:00

commit 1aa574312518ef1d60d2dc62d58f7021db3b163a upstream.

When I repeatedly modprobe and rmmod dax.ko, kmemleak report a
memory leak as follows:

unreferenced object 0xffff9a5588c05088 (size 8):
  comm "modprobe", pid 261, jiffies 4294693644 (age 42.063s)
...
  backtrace:
    [<00000000e007ced0>] kstrdup+0x35/0x70
    [<000000002ae73897>] kstrdup_const+0x3d/0x50
    [<000000002b00c9c3>] kvasprintf_const+0xbc/0xf0
    [<000000008023282f>] kobject_set_name_vargs+0x3b/0xd0
    [<00000000d2cbaa4e>] kobject_set_name+0x62/0x90
    [<00000000202e7a22>] bus_register+0x7f/0x2b0
    [<000000000b77792c>] 0xffffffffc02840f7
    [<000000002d5be5ac>] 0xffffffffc02840b4
    [<00000000dcafb7cd>] do_one_initcall+0x58/0x240
    [<00000000049fe480>] do_init_module+0x56/0x1e2
    [<0000000022671491>] load_module+0x2517/0x2840
    [<000000001a2201cb>] __do_sys_finit_module+0x9c/0xe0
    [<000000003eb304e7>] do_syscall_64+0x33/0x40
    [<0000000051c5fd06>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

When rmmod dax is executed, dax_bus_exit() is missing. This patch
can fix this bug.

Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
Cc: 
Reported-by: Hulk Robot 
Signed-off-by: Wang Hai 
Link: https://lore.kernel.org/r/20201201135929.66530-1-wanghai38@huawei.com
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

dax: Fix alloc_dax_region() compile warning

2020-10-01T11:17:15+00:00

[ Upstream commit 460370ab20b6cc174256e46e192adf01e730faf6 ]

PFN flags are (unsigned long long), fix the alloc_dax_region() calling
convention to fix warnings of the form:

>> include/linux/pfn_t.h:18:17: warning: large integer implicitly truncated to unsigned type [-Woverflow]
    #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))

Reported-by: kbuild test robot 
Signed-off-by: Dan Williams 
Acked-by: Thomas Gleixner 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Sasha Levin

dm: Call proper helper to determine dax support

2020-09-23T10:40:47+00:00

commit e2ec5128254518cae320d5dc631b71b94160f663 upstream.

DM was calling generic_fsdax_supported() to determine whether a device
referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
they don't have to duplicate common generic checks. High level code
should call dax_supported() helper which that calls into appropriate
helper for the particular device. This problem manifested itself as
kernel messages:

dm-3: error: dax access failed (-95)

when lvm2-testsuite run in cases where a DM device was stacked on top of
another DM device.

Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: 
Tested-by: Adrian Huang 
Signed-off-by: Jan Kara 
Acked-by: Mike Snitzer 
Reported-by: kernel test robot 
Link: https://lore.kernel.org/r/160061715195.13131.5503173247632041975.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

device-dax: don't leak kernel memory to user space after unloading kmem

2020-05-27T15:46:48+00:00

commit 60858c00e5f018eda711a3aa84cf62214ef62d61 upstream.

Assume we have kmem configured and loaded:

  [root@localhost ~]# cat /proc/iomem
  ...
  140000000-33fffffff : Persistent Memory$
    140000000-1481fffff : namespace0.0
    150000000-33fffffff : dax0.0
      150000000-33fffffff : System RAM

Assume we try to unload kmem. This force-unloading will work, even if
memory cannot get removed from the system.

  [root@localhost ~]# rmmod kmem
  [   86.380228] removing memory fails, because memory [0x0000000150000000-0x0000000157ffffff] is onlined
  ...
  [   86.431225] kmem dax0.0: DAX region [mem 0x150000000-0x33fffffff] cannot be hotremoved until the next reboot

Now, we can reconfigure the namespace:

  [root@localhost ~]# ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax
  [  131.409351] nd_pmem namespace0.0: could not reserve region [mem 0x140000000-0x33fffffff]dax
  [  131.410147] nd_pmem: probe of namespace0.0 failed with error -16namespace0.0 --mode=devdax
  ...

This fails as expected due to the busy memory resource, and the memory
cannot be used.  However, the dax0.0 device is removed, and along its
name.

The name of the memory resource now points at freed memory (name of the
device):

  [root@localhost ~]# cat /proc/iomem
  ...
  140000000-33fffffff : Persistent Memory
    140000000-1481fffff : namespace0.0
    150000000-33fffffff : �_�^7_��/_��wR��WQ���^��� ...
    150000000-33fffffff : System RAM

We have to make sure to duplicate the string.  While at it, remove the
superfluous setting of the name and fixup a stale comment.

Fixes: 9f960da72b25 ("device-dax: "Hotremove" persistent memory that is used like normal RAM")
Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Cc: Dan Williams 
Cc: Vishal Verma 
Cc: Dave Jiang 
Cc: Pavel Tatashin 
Cc: Andrew Morton 
Cc: 	[5.3]
Link: http://lkml.kernel.org/r/20200508084217.9160-2-david@redhat.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2019-07-19T17:42:02+00:00

Pull vfs mount updates from Al Viro:
 "The first part of mount updates.

  Convert filesystems to use the new mount API"

* 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
  mnt_init(): call shmem_init() unconditionally
  constify ksys_mount() string arguments
  don't bother with registering rootfs
  init_rootfs(): don't bother with init_ramfs_fs()
  vfs: Convert smackfs to use the new mount API
  vfs: Convert selinuxfs to use the new mount API
  vfs: Convert securityfs to use the new mount API
  vfs: Convert apparmorfs to use the new mount API
  vfs: Convert openpromfs to use the new mount API
  vfs: Convert xenfs to use the new mount API
  vfs: Convert gadgetfs to use the new mount API
  vfs: Convert oprofilefs to use the new mount API
  vfs: Convert ibmasmfs to use the new mount API
  vfs: Convert qib_fs/ipathfs to use the new mount API
  vfs: Convert efivarfs to use the new mount API
  vfs: Convert configfs to use the new mount API
  vfs: Convert binfmt_misc to use the new mount API
  convenience helper: get_tree_single()
  convenience helper get_tree_nodev()
  vfs: Kill sget_userns()
  ...

Merge tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2019-07-18T17:58:52+00:00

Pull dax updates from Dan Williams:
 "The fruits of a bug hunt in the fsdax implementation with Willy and a
  small feature update for device-dax:

   - Fix a hang condition that started triggering after the Xarray
     conversion of fsdax in the v4.20 kernel.

   - Add a 'resource' (root-only physical base address) sysfs attribute
     to device-dax instances to correlate memory-blocks onlined via the
     kmem driver with a given device instance"

* tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Fix missed wakeup with PMD faults
  device-dax: Add a 'resource' attribute

Merge tag 'libnvdimm-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2019-07-18T17:52:08+00:00

Pull libnvdimm updates from Dan Williams:
 "Primarily just the virtio_pmem driver:

   - virtio_pmem

     The new virtio_pmem facility introduces a paravirtualized
     persistent memory device that allows a guest VM to use DAX
     mechanisms to access a host-file with host-page-cache. It arranges
     for MAP_SYNC to be disabled and instead triggers a host fsync()
     when a 'write-cache flush' command is sent to the virtual disk
     device.

   - Miscellaneous small fixups"

* tag 'libnvdimm-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  virtio_pmem: fix sparse warning
  xfs: disable map_sync for async flush
  ext4: disable map_sync for async flush
  dax: check synchronous mapping is supported
  dm: enable synchronous dax
  libnvdimm: add dax_dev sync flag
  virtio-pmem: Add virtio pmem driver
  libnvdimm: nd_region flush callback support
  libnvdimm, namespace: Drop uuid_t implementation detail

device-dax: "Hotremove" persistent memory that is used like normal RAM

2019-07-17T02:23:24+00:00

It is now allowed to use persistent memory like a regular RAM, but
currently there is no way to remove this memory until machine is
rebooted.

This work expands the functionality to also allows hotremoving
previously hotplugged persistent memory, and recover the device for use
for other purposes.

To hotremove persistent memory, the management software must first
offline all memory blocks of dax region, and than unbind it from
device-dax/kmem driver.  So, operations should look like this:

  echo offline > /sys/devices/system/memory/memoryN/state
  ...
  echo dax0.0 > /sys/bus/dax/drivers/kmem/unbind

Note: if unbind is done without offlining memory beforehand, it won't be
possible to do dax0.0 hotremove, and dax's memory is going to be part of
System RAM until reboot.

Link: http://lkml.kernel.org/r/20190517215438.6487-4-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin 
Reviewed-by: David Hildenbrand 
Cc: James Morris 
Cc: Sasha Levin 
Cc: Michal Hocko 
Cc: Dave Hansen 
Cc: Dan Williams 
Cc: Keith Busch 
Cc: Vishal Verma 
Cc: Dave Jiang 
Cc: Ross Zwisler 
Cc: Tom Lendacky 
Cc: Huang Ying 
Cc: Fengguang Wu 
Cc: Borislav Petkov 
Cc: Bjorn Helgaas 
Cc: Yaowei Bai 
Cc: Takashi Iwai 
Cc: Jérôme Glisse 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

device-dax: fix memory and resource leak if hotplug fails

2019-07-17T02:23:24+00:00

Patch series ""Hotremove" persistent memory", v6.

Recently, adding a persistent memory to be used like a regular RAM was
added to Linux.  This work extends this functionality to also allow hot
removing persistent memory.

We (Microsoft) have an important use case for this functionality.

The requirement is for physical machines with small amount of RAM (~8G)
to be able to reboot in a very short period of time (<1s).  Yet, there
is a userland state that is expensive to recreate (~2G).

The solution is to boot machines with 2G preserved for persistent
memory.

Copy the state, and hotadd the persistent memory so machine still has
all 8G available for runtime.  Before reboot, offline and hotremove
device-dax 2G, copy the memory that is needed to be preserved to pmem0
device, and reboot.

The series of operations look like this:

1. After boot restore /dev/pmem0 to ramdisk to be consumed by apps.
   and free ramdisk.
2. Convert raw pmem0 to devdax
   ndctl create-namespace --mode devdax --map mem -e namespace0.0 -f
3. Hotadd to System RAM
   echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
   echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id
   echo online_movable > /sys/devices/system/memoryXXX/state
4. Before reboot hotremove device-dax memory from System RAM
   echo offline > /sys/devices/system/memoryXXX/state
   echo dax0.0 > /sys/bus/dax/drivers/kmem/unbind
5. Create raw pmem0 device
   ndctl create-namespace --mode raw  -e namespace0.0 -f
6. Copy the state that was stored by apps to ramdisk to pmem device
7. Do kexec reboot or reboot through firmware if firmware does not
   zero memory in pmem0 region (These machines have only regular
   volatile memory). So to have pmem0 device either memmap kernel
   parameter is used, or devices nodes in dtb are specified.

This patch (of 3):

When add_memory() fails, the resource and the memory should be freed.

Link: http://lkml.kernel.org/r/20190517215438.6487-2-pasha.tatashin@soleen.com
Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM")
Signed-off-by: Pavel Tatashin 
Reviewed-by: Dave Hansen 
Cc: Bjorn Helgaas 
Cc: Borislav Petkov 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: Dave Jiang 
Cc: David Hildenbrand 
Cc: Fengguang Wu 
Cc: Huang Ying 
Cc: James Morris 
Cc: Jérôme Glisse 
Cc: Keith Busch 
Cc: Michal Hocko 
Cc: Ross Zwisler 
Cc: Sasha Levin 
Cc: Takashi Iwai 
Cc: Tom Lendacky 
Cc: Vishal Verma 
Cc: Yaowei Bai 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds