| Commit message (Collapse) | Author | Age | Files | Lines |
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We want dax capable drivers to be able to publish a set of dax
operations [1]. However, we do not want to further abuse block_devices
to advertise these operations. Instead we will attach these operations
to a dax device and add a lookup mechanism to go from block device path
to a dax device. A dax capable driver like pmem or brd is responsible
for registering a dax device, alongside a block device, and then a dax
capable filesystem is responsible for retrieving the dax device by path
name if it wants to call dax_operations.
For now, we refactor the dax pseudo-fs to be a generic facility, rather
than an implementation detail, of the device-dax use case. Where a "dax
device" is just an inode + dax infrastructure, and "Device DAX" is a
mapping service layered on top of that base 'struct dax_device'.
"Filesystem DAX" is then a mapping service that layers a filesystem on
top of that same base device. Filesystem DAX is associated with a
block_device for now, but perhaps directly to a dax device in the
future, or for new pmem-only filesystems.
[1]: https://lkml.org/lkml/2017/1/19/880
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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In preparation for introducing a struct dax_device type to the kernel
global type namespace, rename dax_dev to dev_dax. A 'dax_device'
instance will be a generic device-driver object for any provider of dax
functionality. A 'dev_dax' object is a device-dax-driver local /
internal instance.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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A couple of minor improvements to the debug output in the fault handlers:
a) Print the region alignment and fault size when we sent a SIGBUS
because the region alignment is greater than the fault size.
b) Fix the message in the PFN_{DEV|MAP} check.
c) Additionally print the fault size enum value in the huge fault handler.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The default case for dax_dev_huge_fault() fault size handling mistakenly
returns when it should unlock. This is not a problem in practice since
the only three possible fault sizes are handled. Going forward, if the
core mm adds a new fault size beyond pte, pmd, or pud device-dax should
abort VM_FAULT_SIGBUS requests not VM_FAULT_FALLBACK since device-dax
guarantees a configured fault granularity for all faults.
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The following warning triggers with a new unit test that stresses the
device-dax interface.
===============================
[ ERR: suspicious RCU usage. ]
4.11.0-rc4+ #1049 Tainted: G O
-------------------------------
./include/linux/rcupdate.h:521 Illegal context switch in RCU read-side critical section!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 0
2 locks held by fio/9070:
#0: (&mm->mmap_sem){++++++}, at: [<ffffffff8d0739d7>] __do_page_fault+0x167/0x4f0
#1: (rcu_read_lock){......}, at: [<ffffffffc03fbd02>] dax_dev_huge_fault+0x32/0x620 [dax]
Call Trace:
dump_stack+0x86/0xc3
lockdep_rcu_suspicious+0xd7/0x110
___might_sleep+0xac/0x250
__might_sleep+0x4a/0x80
__alloc_pages_nodemask+0x23a/0x360
alloc_pages_current+0xa1/0x1f0
pte_alloc_one+0x17/0x80
__pte_alloc+0x1e/0x120
__get_locked_pte+0x1bf/0x1d0
insert_pfn.isra.70+0x3a/0x100
? lookup_memtype+0xa6/0xd0
vm_insert_mixed+0x64/0x90
dax_dev_huge_fault+0x520/0x620 [dax]
? dax_dev_huge_fault+0x32/0x620 [dax]
dax_dev_fault+0x10/0x20 [dax]
__do_fault+0x1e/0x140
__handle_mm_fault+0x9af/0x10d0
handle_mm_fault+0x16d/0x370
? handle_mm_fault+0x47/0x370
__do_page_fault+0x28c/0x4f0
trace_do_page_fault+0x58/0x2a0
do_async_page_fault+0x1a/0xa0
async_page_fault+0x28/0x30
Inserting a page table entry may trigger an allocation while we are
holding a read lock to keep the device instance alive for the duration
of the fault. Use srcu for this keep-alive protection.
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The debug output for return the return data of pgoff_to_phys() in the
fault handlers has 'phys' and 'pgoff' incorrectly swapped.
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Jeff Moyer reports:
With a device dax alignment of 4KB or 2MB, I get sigbus when running
the attached fio job file for the current kernel (4.11.0-rc1+). If
I specify an alignment of 1GB, it works.
I turned on debug output, and saw that it was failing in the huge
fault code.
dax dax1.0: dax_open
dax dax1.0: dax_mmap
dax dax1.0: dax_dev_huge_fault: fio: write (0x7f08f0a00000 -
dax dax1.0: __dax_dev_pud_fault: phys_to_pgoff(0xffffffffcf60)
dax dax1.0: dax_release
fio config for reproduce:
[global]
ioengine=dev-dax
direct=0
filename=/dev/dax0.0
bs=2m
[write]
rw=write
[read]
stonewall
rw=read
The driver fails to fallback when taking a fault that is larger than
the device alignment, or handling a larger fault when a smaller
mapping is already established. While we could support larger
mappings for a device with a smaller alignment, that change is
too large for the immediate fix. The simplest change is to force
fallback until the fault size matches the alignment.
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Jeff Moyer reports:
With a device dax alignment of 4KB or 2MB, I get sigbus when running
the attached fio job file for the current kernel (4.11.0-rc1+). If
I specify an alignment of 1GB, it works.
I turned on debug output, and saw that it was failing in the huge
fault code.
dax dax1.0: dax_open
dax dax1.0: dax_mmap
dax dax1.0: dax_dev_huge_fault: fio: write (0x7f08f0a00000 -
dax dax1.0: __dax_dev_pud_fault: phys_to_pgoff(0xffffffffcf60
dax dax1.0: dax_release
fio config for reproduce:
[global]
ioengine=dev-dax
direct=0
filename=/dev/dax0.0
bs=2m
[write]
rw=write
[read]
stonewall
rw=read
The driver fails to fallback when taking a fault that is larger than
the device alignment, or handling a larger fault when a smaller
mapping is already established. While we could support larger
mappings for a device with a smaller alignment, that change is
too large for the immediate fix. The simplest change is to force
fallback until the fault size matches the alignment.
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Cc: <stable@vger.kernel.org>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Replace the open coded registration of the cdev and dev with the
new device_add_cdev() helper. The helper replaces a common pattern by
taking the proper reference against the parent device and adding both
the cdev and the device.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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If device_add() fails, cleanup the cdev. Otherwise, we leak a kobj_map()
with a stale device number.
As Jason points out, there is a small possibility that userspace has
opened and mapped the device in the time between cdev_add() and the
device_add() failure. We need a new kill_dax_dev() helper to invalidate
any established mappings.
Fixes: ba09c01d2fa8 ("dax: convert to the cdev api")
Cc: <stable@vger.kernel.org>
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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<linux/sched/task_stack.h>
Update files that depend on the magic.h inclusion.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Since the introduction of FAULT_FLAG_SIZE to the vm_fault flag, it has
been somewhat painful with getting the flags set and removed at the
correct locations. More than one kernel oops was introduced due to
difficulties of getting the placement correctly.
Remove the flag values and introduce an input parameter to huge_fault
that indicates the size of the page entry. This makes the code easier
to trace and should avoid the issues we see with the fault flags where
removal of the flag was necessary in the fallback paths.
Link: http://lkml.kernel.org/r/148615748258.43180.1690152053774975329.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add transparent huge PUD pages support for device DAX by adding a
pud_fault handler.
Link: http://lkml.kernel.org/r/148545060002.17912.6765687780007547551.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "1G transparent hugepage support for device dax", v2.
The following series implements support for 1G trasparent hugepage on
x86 for device dax. The bulk of the code was written by Mathew Wilcox a
while back supporting transparent 1G hugepage for fs DAX. I have
forward ported the relevant bits to 4.10-rc. The current submission has
only the necessary code to support device DAX.
Comments from Dan Williams: So the motivation and intended user of this
functionality mirrors the motivation and users of 1GB page support in
hugetlbfs. Given expected capacities of persistent memory devices an
in-memory database may want to reduce tlb pressure beyond what they can
already achieve with 2MB mappings of a device-dax file. We have
customer feedback to that effect as Willy mentioned in his previous
version of these patches [1].
[1]: https://lkml.org/lkml/2016/1/31/52
Comments from Nilesh @ Oracle:
There are applications which have a process model; and if you assume
10,000 processes attempting to mmap all the 6TB memory available on a
server; we are looking at the following:
processes : 10,000
memory : 6TB
pte @ 4k page size: 8 bytes / 4K of memory * #processes = 6TB / 4k * 8 * 10000 = 1.5GB * 80000 = 120,000GB
pmd @ 2M page size: 120,000 / 512 = ~240GB
pud @ 1G page size: 240GB / 512 = ~480MB
As you can see with 2M pages, this system will use up an exorbitant
amount of DRAM to hold the page tables; but the 1G pages finally brings
it down to a reasonable level. Memory sizes will keep increasing; so
this number will keep increasing.
An argument can be made to convert the applications from process model
to thread model, but in the real world that may not be always practical.
Hopefully this helps explain the use case where this is valuable.
This patch (of 3):
In preparation for adding the ability to handle PUD pages, convert
vm_operations_struct.pmd_fault to vm_operations_struct.huge_fault. The
vm_fault structure is extended to include a union of the different page
table pointers that may be needed, and three flag bits are reserved to
indicate which type of pointer is in the union.
[ross.zwisler@linux.intel.com: remove unused function ext4_dax_huge_fault()]
Link: http://lkml.kernel.org/r/1485813172-7284-1-git-send-email-ross.zwisler@linux.intel.com
[dave.jiang@intel.com: clear PMD or PUD size flags when in fall through path]
Link: http://lkml.kernel.org/r/148589842696.5820.16078080610311444794.stgit@djiang5-desk3.ch.intel.com
Link: http://lkml.kernel.org/r/148545058784.17912.6353162518188733642.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.
Remove the vma parameter to simplify things.
[arnd@arndb.de: fix ARM build]
Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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pmd_fault() and related functions really only need the vmf parameter since
the additional parameters are all included in the vmf struct. Remove the
additional parameter and simplify pmd_fault() and friends.
Link: http://lkml.kernel.org/r/1484085142-2297-8-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Instead of passing in multiple parameters in the pmd_fault() handler,
a vmf can be passed in just like a fault() handler. This will simplify
code and remove the need for the actual pmd fault handlers to allocate a
vmf. Related functions are also modified to do the same.
[dave.jiang@intel.com: fix issue with xfs_tests stall when DAX option is off]
Link: http://lkml.kernel.org/r/148469861071.195597.3619476895250028518.stgit@djiang5-desk3.ch.intel.com
Link: http://lkml.kernel.org/r/1484085142-2297-7-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm updates from Dan Williams:
"The libnvdimm pull request is relatively small this time around due to
some development topics being deferred to 4.11.
As for this pull request the bulk of it has been in -next for several
releases leading to one late fix being added (commit 868f036fee4b
("libnvdimm: fix mishandled nvdimm_clear_poison() return value")). It
has received a build success notification from the 0day-kbuild robot
and passes the latest libnvdimm unit tests.
Summary:
- Dynamic label support: To date namespace label support has been
limited to disambiguating cases where PMEM (direct load/store) and
BLK (mmio aperture) accessed-capacity alias on the same DIMM. Since
4.9 added support for multiple namespaces per PMEM-region there is
value to support namespace labels even in the non-aliasing case.
The presence of a valid namespace index block force-enables label
support when the kernel would otherwise rely on region boundaries,
and permits the region to be sub-divided.
- Handle media errors in namespace metadata: Complement the error
handling for media errors in namespace data areas with support for
clearing errors on writes, and downgrading potential machine-check
exceptions to simple i/o errors on read.
- Device-DAX region attributes: Add 'align', 'id', and 'size' as
attributes for device-dax regions. In particular this enables
userspace tooling to generically size memory mapping and i/o
operations. Prevent userspace from growing assumptions /
dependencies about the parent device topology for a dax region. A
libnvdimm namespace may not always be the parent device of a dax
region.
- Various cleanups and small fixes"
* tag 'libnvdimm-for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
dax: add region 'id', 'size', and 'align' attributes
libnvdimm: fix mishandled nvdimm_clear_poison() return value
libnvdimm: replace mutex_is_locked() warnings with lockdep_assert_held
libnvdimm, pfn: fix align attribute
libnvdimm, e820: use module_platform_driver
libnvdimm, namespace: use octal for permissions
libnvdimm, namespace: avoid multiple sector calculations
libnvdimm: remove else after return in nsio_rw_bytes()
libnvdimm, namespace: fix the type of name variable
libnvdimm: use consistent naming for request_mem_region()
nvdimm: use the right length of "pmem"
libnvdimm: check and clear poison before writing to pmem
tools/testing/nvdimm: dynamic label support
libnvdimm: allow a platform to force enable label support
libnvdimm: use generic iostat interfaces
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While this information is available by looking at the nvdimm parent
device that may not always be the case when/if we add support for other
memory regions. Tooling should not depend on walking a given ancestor
topology that is not guaranteed by the device's class. For example, a
device-dax instance will always have a dax_region parent, but it may not
always have a libnvdimm "dax" device as a grandparent.
Reported-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Every single user of vmf->virtual_address typed that entry to unsigned
long before doing anything with it so the type of virtual_address does
not really provide us any additional safety. Just use masked
vmf->address which already has the appropriate type.
Link: http://lkml.kernel.org/r/1479460644-25076-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Hugh notes in response to commit 4cb19355ea19 "device-dax: fail all
private mapping attempts":
"I think that is more restrictive than you intended: haven't tried, but I
believe it rejects a PROT_READ, MAP_SHARED, O_RDONLY fd mmap, leaving no
way to mmap /dev/dax without write permission to it."
Indeed it does restrict read-only mappings, switch to checking
VM_MAYSHARE, not VM_SHARED.
Cc: <stable@vger.kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Fixes: 4cb19355ea19 ("device-dax: fail all private mapping attempts")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The device-dax implementation originally tried to be tricky and allow
private read-only mappings, but in the process allowed writable
MAP_PRIVATE + MAP_NORESERVE mappings. For simplicity and predictability
just fail all private mapping attempts since device-dax memory is
statically allocated and will never support overcommit.
Cc: <stable@vger.kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Reported-by: Pawel Lebioda <pawel.lebioda@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The dev_t variable in devm_create_dax_dev() is used before it's
first set:
drivers/dax/dax.c: In function 'devm_create_dax_dev':
drivers/dax/dax.c:205:39: error: 'dev_t' may be used uninitialized in this function [-Werror=maybe-uninitialized]
inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/dax/dax.c:688:8: note: 'dev_t' was declared here
This reorders the code to how it looks correct to me.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 3bc52c45bac2 ("dax: define a unified inode/address_space for device-dax mappings")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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For sub-division support we need access to the dax_dev created by
devm_create_dax_dev().
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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All the extents of a dax-device must match the alignment of the region.
Otherwise, we are unable to guarantee fault semantics of a given page
size. The region must be self-consistent itself as well.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Invalidate all mappings of a device-dax instance when the device is
unregistered.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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In support of enabling resize / truncate of device-dax instances, define
a pseudo-fs to provide a unified inode/address space for vm operations.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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A goal of the device-DAX interface is to be able to support many
exclusive allocations (partitions) of performance / feature
differentiated memory. This count may exceed the default minors limit
of 256.
As a result of switching to an embedded cdev the inode-to-dax_dev
conversion is simplified, as well as reference counting which can switch
to the cdev kobject lifetime.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The kref in dax_dev can be made redundant if the final put_device() on
the device associated with the dax_dev frees the dax_dev. This can be
accomplished by embedding a struct device in struct dax_dev, open coding
device_create() and specifying a custom release method.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Shorten the prefix of the file operations to distinguish them from
operations on the struct device associated with the dax_dev.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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In order to convert devm_create_dax_dev() to use cdev, it will need
access to dax_fops. Move dax_fops and related function definitions
before devm_create_dax_dev().
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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drivers/dax/dax.c:75:6: warning: symbol 'dax_region_put' was not declared.
drivers/dax/dax.c:95:19: warning: symbol 'alloc_dax_region' was not declared.
drivers/dax/dax.c:173:5: warning: symbol 'devm_create_dax_dev' was not declared.
drivers/dax/pmem.c:27:17: warning: symbol 'to_dax_pmem' was not declared.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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pgoff_to_phys() validates that both the starting address and the length
of the mapping against the resource list. We need to check for a
mapping size of PMD_SIZE not PAGE_SIZE in the pmd fault path.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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If devm_add_action() fails, we are explicitly calling the cleanup to free
the resources allocated. Use the helper devm_add_action_or_reset()
and return directly in case of error, since the cleanup function
has been already called by the helper if there was any error.
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Vikas C Sajjan <vikas.cha.sajjan@hpe.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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The "Device DAX" core enables dax mappings of performance / feature
differentiated memory. An open mapping or file handle keeps the backing
struct device live, but new mappings are only possible while the device
is enabled. Faults are handled under rcu_read_lock to synchronize
with the enabled state of the device.
Similar to the filesystem-dax case the backing memory may optionally
have struct page entries. However, unlike fs-dax there is no support
for private mappings, or mappings that are not backed by media (see
use of zero-page in fs-dax).
Mappings are always guaranteed to match the alignment of the dax_region.
If the dax_region is configured to have a 2MB alignment, all mappings
are guaranteed to be backed by a pmd entry. Contrast this determinism
with the fs-dax case where pmd mappings are opportunistic. If userspace
attempts to force a misaligned mapping, the driver will fail the mmap
attempt. See dax_dev_check_vma() for other scenarios that are rejected,
like MAP_PRIVATE mappings.
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX). It allows memory ranges to be allocated and mapped
without need of an intervening file system. Device DAX is strict,
precise and predictable. Specifically this interface:
1/ Guarantees fault granularity with respect to a given page size (pte,
pmd, or pud) set at configuration time.
2/ Enforces deterministic behavior by being strict about what fault
scenarios are supported.
For example, by forcing MADV_DONTFORK semantics and omitting MAP_PRIVATE
support device-dax guarantees that a mapping always behaves/performs the
same once established. It is the "what you see is what you get" access
mechanism to differentiated memory vs filesystem DAX which has
filesystem specific implementation semantics.
Persistent memory is the first target, but the mechanism is also
targeted for exclusive allocations of performance differentiated memory
ranges.
This commit is limited to the base device driver infrastructure to
associate a dax device with pmem range.
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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