linux-toradex.git/drivers/dax/device.c, branch v5.9-rc5

memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC

2020-09-04T07:59:59+00:00

This is in preparation for the logic behind MEMORY_DEVICE_DEVDAX also
being used by non DAX devices.

No functional change intended.

Signed-off-by: Roger Pau Monné 
Reviewed-by: Ira Weiny 
Acked-by: Andrew Morton 
Reviewed-by: Pankaj Gupta 
Link: https://lore.kernel.org/r/20200901083326.21264-3-roger.pau@citrix.com
Signed-off-by: Juergen Gross

vfs: track per-sb writeback errors and report them to syncfs

2020-06-02T17:59:05+00:00

Patch series "vfs: have syncfs() return error when there are writeback
errors", v6.

Currently, syncfs does not return errors when one of the inodes fails to
be written back.  It will return errors based on the legacy AS_EIO and
AS_ENOSPC flags when syncing out the block device fails, but that's not
particularly helpful for filesystems that aren't backed by a blockdev.
It's also possible for a stray sync to lose those errors.

The basic idea in this set is to track writeback errors at the
superblock level, so that we can quickly and easily check whether
something bad happened without having to fsync each file individually.
syncfs is then changed to reliably report writeback errors after they
occur, much in the same fashion as fsync does now.

This patch (of 2):

Usually we suggest that applications call fsync when they want to ensure
that all data written to the file has made it to the backing store, but
that can be inefficient when there are a lot of open files.

Calling syncfs on the filesystem can be more efficient in some
situations, but the error reporting doesn't currently work the way most
people expect.  If a single inode on a filesystem reports a writeback
error, syncfs won't necessarily return an error.  syncfs only returns an
error if __sync_blockdev fails, and on some filesystems that's a no-op.

It would be better if syncfs reported an error if there were any
writeback failures.  Then applications could call syncfs to see if there
are any errors on any open files, and could then call fsync on all of
the other descriptors to figure out which one failed.

This patch adds a new errseq_t to struct super_block, and has
mapping_set_error also record writeback errors there.

To report those errors, we also need to keep an errseq_t in struct file
to act as a cursor.  This patch adds a dedicated field for that purpose,
which slots nicely into 4 bytes of padding at the end of struct file on
x86_64.

An earlier version of this patch used an O_PATH file descriptor to cue
the kernel that the open file should track the superblock error and not
the inode's writeback error.

I think that API is just too weird though.  This is simpler and should
make syncfs error reporting "just work" even if someone is multiplexing
fsync and syncfs on the same fds.

Signed-off-by: Jeff Layton 
Signed-off-by: Andrew Morton 
Reviewed-by: Jan Kara 
Cc: Andres Freund 
Cc: Matthew Wilcox 
Cc: Al Viro 
Cc: Christoph Hellwig 
Cc: Dave Chinner 
Cc: David Howells 
Link: http://lkml.kernel.org/r/20200428135155.19223-1-jlayton@kernel.org
Link: http://lkml.kernel.org/r/20200428135155.19223-2-jlayton@kernel.org
Signed-off-by: Linus Torvalds

device-dax: use the dev_pagemap internal refcount

2019-07-02T17:32:44+00:00

The functionality is identical to the one currently open coded in
device-dax.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ira Weiny 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: pass a struct dev_pagemap to ->kill and ->cleanup

2019-07-02T17:32:44+00:00

Passing the actual typed structure leads to more understandable code
vs just passing the ref member.

Reported-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: move dev_pagemap callbacks into a separate structure

2019-07-02T17:32:44+00:00

The dev_pagemap is a growing too many callbacks.  Move them into a
separate ops structure so that they are not duplicated for multiple
instances, and an attacker can't easily overwrite them.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: validate the pagemap type passed to devm_memremap_pages

2019-07-02T17:32:44+00:00

Most pgmap types are only supported when certain config options are
enabled.  Check for a type that is valid for the current configuration
before setting up the pagemap.  For this the usage of the 0 type for
device dax gets replaced with an explicit MEMORY_DEVICE_DEVDAX type.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ira Weiny 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

mm/devm_memremap_pages: fix final page put race

2019-06-14T03:34:56+00:00

Logan noticed that devm_memremap_pages_release() kills the percpu_ref
drops all the page references that were acquired at init and then
immediately proceeds to unplug, arch_remove_memory(), the backing pages
for the pagemap.  If for some reason device shutdown actually collides
with a busy / elevated-ref-count page then arch_remove_memory() should
be deferred until after that reference is dropped.

As it stands the "wait for last page ref drop" happens *after*
devm_memremap_pages_release() returns, which is obviously too late and
can lead to crashes.

Fix this situation by assigning the responsibility to wait for the
percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup()
callback.  Implement the new cleanup callback for all
devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma.

Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a851304 ("add devm_memremap_pages")
Signed-off-by: Dan Williams 
Reported-by: Logan Gunthorpe 
Reviewed-by: Ira Weiny 
Reviewed-by: Logan Gunthorpe 
Cc: Bjorn Helgaas 
Cc: "Jérôme Glisse" 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/huge_memory: fix vmf_insert_pfn_{pmd, pud}() crash, handle unaligned addresses

2019-05-14T16:47:44+00:00

Starting with c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page
protection by insert_pfn_pmd()") vmf_insert_pfn_pmd() internally calls
pmdp_set_access_flags().  That helper enforces a pmd aligned @address
argument via VM_BUG_ON() assertion.

Update the implementation to take a 'struct vm_fault' argument directly
and apply the address alignment fixup internally to fix crash signatures
like:

    kernel BUG at arch/x86/mm/pgtable.c:515!
    invalid opcode: 0000 [#1] SMP NOPTI
    CPU: 51 PID: 43713 Comm: java Tainted: G           OE     4.19.35 #1
    [..]
    RIP: 0010:pmdp_set_access_flags+0x48/0x50
    [..]
    Call Trace:
     vmf_insert_pfn_pmd+0x198/0x350
     dax_iomap_fault+0xe82/0x1190
     ext4_dax_huge_fault+0x103/0x1f0
     ? __switch_to_asm+0x40/0x70
     __handle_mm_fault+0x3f6/0x1370
     ? __switch_to_asm+0x34/0x70
     ? __switch_to_asm+0x40/0x70
     handle_mm_fault+0xda/0x200
     __do_page_fault+0x249/0x4f0
     do_page_fault+0x32/0x110
     ? page_fault+0x8/0x30
     page_fault+0x1e/0x30

Link: http://lkml.kernel.org/r/155741946350.372037.11148198430068238140.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page protection by insert_pfn_pmd()")
Signed-off-by: Dan Williams 
Reported-by: Piotr Balcer 
Tested-by: Yan Ma 
Tested-by: Pankaj Gupta 
Reviewed-by: Matthew Wilcox 
Reviewed-by: Jan Kara 
Reviewed-by: Aneesh Kumar K.V 
Cc: Chandan Rajendra 
Cc: Souptick Joarder 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

device-dax: Add /sys/class/dax backwards compatibility

2019-01-07T05:41:57+00:00

On the expectation that some environments may not upgrade libdaxctl
(userspace component that depends on the /sys/class/dax hierarchy),
provide a default / legacy dax_pmem_compat driver. The dax_pmem_compat
driver implements the original /sys/class/dax sysfs layout rather than
/sys/bus/dax. When userspace is upgraded it can blacklist this module
and switch to the dax_pmem driver going forward.

CONFIG_DEV_DAX_PMEM_COMPAT and supporting code will be deleted according
to the dax_pmem entry in Documentation/ABI/obsolete/.

Signed-off-by: Dan Williams

device-dax: Add support for a dax override driver

2019-01-07T05:41:55+00:00

Introduce the 'new_id' concept for enabling a custom device-driver attach
policy for dax-bus drivers. The intended use is to have a mechanism for
hot-plugging device-dax ranges into the page allocator on-demand. With
this in place the default policy of using device-dax for performance
differentiated memory can be overridden by user-space policy that can
arrange for the memory range to be managed as 'System RAM' with
user-defined NUMA and other performance attributes.

Signed-off-by: Dan Williams