[ Upstream commit 1a14e3779dd58c16b30e56558146e5cc850ba8b0 ]
grab_mapping_entry() has a bug in handling of ENOMEM condition. Suppose
we have a PMD entry at index i which we are downgrading to a PTE entry.
grab_mapping_entry() will set pmd_downgrade to true, lock the entry, clear
the entry in xarray, and decrement mapping->nrpages. The it will call:
entry = dax_make_entry(pfn_to_pfn_t(0), flags);
dax_lock_entry(xas, entry);
which inserts new PTE entry into xarray. However this may fail allocating
the new node. We handle this by:
if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM))
goto retry;
however pmd_downgrade stays set to true even though 'entry' returned from
get_unlocked_entry() will be NULL now. And we will go again through the
downgrade branch. This is mostly harmless except that mapping->nrpages is
decremented again and we temporarily have an invalid entry stored in
xarray. Fix the problem by setting pmd_downgrade to false each time we
lookup the entry we work with so that it matches the entry we found.
Link: https://lkml.kernel.org/r/20210622160015.18004-1-jack@suse.cz
Fixes: b15cd80068 ("dax: Convert page fault handlers to XArray")
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 9fd6dad1261a541b3f5fa7dc5b152222306e6702 upstream.
Currently, the follow_pfn function is exported for modules but
follow_pte is not. However, follow_pfn is very easy to misuse,
because it does not provide protections (so most of its callers
assume the page is writable!) and because it returns after having
already unlocked the page table lock.
Provide instead a simplified version of follow_pte that does
not have the pmdpp and range arguments. The older version
survives as follow_invalidate_pte() for use by fs/dax.c.
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ff5c19ed4b087073cea38ff0edc80c23d7256943 upstream.
Merge __follow_pte_pmd, follow_pte_pmd and follow_pte into a single
follow_pte function and just pass two additional NULL arguments for the
two previous follow_pte callers.
[sfr@canb.auug.org.au: merge fix for "s390/pci: remove races against pte updates"]
Link: https://lkml.kernel.org/r/20201111221254.7f6a3658@canb.auug.org.au
Link: https://lkml.kernel.org/r/20201029101432.47011-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 96222d53842dfe54869ec4e1b9d4856daf9105a2 ]
fstests generic/471 reports a failure when run with MOUNT_OPTIONS="-o
dax". The reason is that the initial pwrite to an empty file with the
RWF_NOWAIT flag set does not return -EAGAIN. It turns out that
dax_iomap_rw doesn't pass that flag through to iomap_apply.
With this patch applied, generic/471 passes for me.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/x49r1z86e1d.fsf@segfault.boston.devel.redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Users reported a v5.3 performance regression and inability to establish
huge page mappings. A revised version of the ndctl "dax.sh" huge page
unit test identifies commit 23c84eb783 "dax: Fix missed wakeup with
PMD faults" as the source.
Update get_unlocked_entry() to check for NULL entries before checking
the entry order, otherwise NULL is misinterpreted as a present pte
conflict. The 'order' check needs to happen before the locked check as
an unlocked entry at the wrong order must fallback to lookup the correct
order.
Reported-by: Jeff Smits <jeff.smits@intel.com>
Reported-by: Doug Nelson <doug.nelson@intel.com>
Cc: <stable@vger.kernel.org>
Fixes: 23c84eb783 ("dax: Fix missed wakeup with PMD faults")
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Link: https://lore.kernel.org/r/157167532455.3945484.11971474077040503994.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Vivek:
"As of now dax_layout_busy_page() calls unmap_mapping_range() with last
argument as 1, which says even unmap cow pages. I am wondering who needs
to get rid of cow pages as well.
I noticed one interesting side affect of this. I mount xfs with -o dax and
mmaped a file with MAP_PRIVATE and wrote some data to a page which created
cow page. Then I called fallocate() on that file to zero a page of file.
fallocate() called dax_layout_busy_page() which unmapped cow pages as well
and then I tried to read back the data I wrote and what I get is old
data from persistent memory. I lost the data I had written. This
read basically resulted in new fault and read back the data from
persistent memory.
This sounds wrong. Are there any users which need to unmap cow pages
as well? If not, I am proposing changing it to not unmap cow pages.
I noticed this while while writing virtio_fs code where when I tried
to reclaim a memory range and that corrupted the executable and I
was running from virtio-fs and program got segment violation."
Dan:
"In fact the unmap_mapping_range() in this path is only to synchronize
against get_user_pages_fast() and force it to call back into the
filesystem to re-establish the mapping. COW pages should be left
untouched by dax_layout_busy_page()."
Cc: <stable@vger.kernel.org>
Fixes: 5fac7408d8 ("mm, fs, dax: handle layout changes to pinned dax mappings")
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20190802192956.GA3032@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The condition checking whether put_unlocked_entry() needs to wake up
following waiter got broken by commit 23c84eb783 ("dax: Fix missed
wakeup with PMD faults"). We need to wake the waiter whenever the passed
entry is valid (i.e., non-NULL and not special conflict entry). This
could lead to processes never being woken up when waiting for entry
lock. Fix the condition.
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/20190729120228.GC17833@quack2.suse.cz
Fixes: 23c84eb783 ("dax: Fix missed wakeup with PMD faults")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
- Regroup the fs/iomap.c code by major functional area so that we can
start development for 5.4 from a more stable base.
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Merge tag 'iomap-5.3-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull iomap split/cleanup from Darrick Wong:
"As promised, here's the second part of the iomap merge for 5.3, in
which we break up iomap.c into smaller files grouped by functional
area so that it'll be easier in the long run to maintain cohesiveness
of code units and to review incoming patches. There are no functional
changes and fs/iomap.c split cleanly.
Summary:
- Regroup the fs/iomap.c code by major functional area so that we can
start development for 5.4 from a more stable base"
* tag 'iomap-5.3-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
iomap: move internal declarations into fs/iomap/
iomap: move the main iteration code into a separate file
iomap: move the buffered IO code into a separate file
iomap: move the direct IO code into a separate file
iomap: move the SEEK_HOLE code into a separate file
iomap: move the file mapping reporting code into a separate file
iomap: move the swapfile code into a separate file
iomap: start moving code to fs/iomap/
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.
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Merge tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
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
Move internal function declarations out of fs/internal.h into
include/linux/iomap.h so that our transition is complete.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
RocksDB can hang indefinitely when using a DAX file. This is due to
a bug in the XArray conversion when handling a PMD fault and finding a
PTE entry. We use the wrong index in the hash and end up waiting on
the wrong waitqueue.
There's actually no need to wait; if we find a PTE entry while looking
for a PMD entry, we can return immediately as we know we should fall
back to a PTE fault (which may not conflict with the lock held).
We reuse the XA_RETRY_ENTRY to signal a conflicting entry was found.
This value can never be found in an XArray while holding its lock, so
it does not create an ambiguity.
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/CAPcyv4hwHpX-MkUEqxwdTj7wCCZCN4RV-L4jsnuwLGyL_UEG4A@mail.gmail.com
Fixes: b15cd80068 ("dax: Convert page fault handlers to XArray")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Robert Barror <robert.barror@intel.com>
Reported-by: Seema Pandit <seema.pandit@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Pull locking updates from Ingo Molnar:
"The main changes in this cycle are:
- rwsem scalability improvements, phase #2, by Waiman Long, which are
rather impressive:
"On a 2-socket 40-core 80-thread Skylake system with 40 reader
and writer locking threads, the min/mean/max locking operations
done in a 5-second testing window before the patchset were:
40 readers, Iterations Min/Mean/Max = 1,807/1,808/1,810
40 writers, Iterations Min/Mean/Max = 1,807/50,344/151,255
After the patchset, they became:
40 readers, Iterations Min/Mean/Max = 30,057/31,359/32,741
40 writers, Iterations Min/Mean/Max = 94,466/95,845/97,098"
There's a lot of changes to the locking implementation that makes
it similar to qrwlock, including owner handoff for more fair
locking.
Another microbenchmark shows how across the spectrum the
improvements are:
"With a locking microbenchmark running on 5.1 based kernel, the
total locking rates (in kops/s) on a 2-socket Skylake system
with equal numbers of readers and writers (mixed) before and
after this patchset were:
# of Threads Before Patch After Patch
------------ ------------ -----------
2 2,618 4,193
4 1,202 3,726
8 802 3,622
16 729 3,359
32 319 2,826
64 102 2,744"
The changes are extensive and the patch-set has been through
several iterations addressing various locking workloads. There
might be more regressions, but unless they are pathological I
believe we want to use this new implementation as the baseline
going forward.
- jump-label optimizations by Daniel Bristot de Oliveira: the primary
motivation was to remove IPI disturbance of isolated RT-workload
CPUs, which resulted in the implementation of batched jump-label
updates. Beyond the improvement of the real-time characteristics
kernel, in one test this patchset improved static key update
overhead from 57 msecs to just 1.4 msecs - which is a nice speedup
as well.
- atomic64_t cross-arch type cleanups by Mark Rutland: over the last
~10 years of atomic64_t existence the various types used by the
APIs only had to be self-consistent within each architecture -
which means they became wildly inconsistent across architectures.
Mark puts and end to this by reworking all the atomic64
implementations to use 's64' as the base type for atomic64_t, and
to ensure that this type is consistently used for parameters and
return values in the API, avoiding further problems in this area.
- A large set of small improvements to lockdep by Yuyang Du: type
cleanups, output cleanups, function return type and othr cleanups
all around the place.
- A set of percpu ops cleanups and fixes by Peter Zijlstra.
- Misc other changes - please see the Git log for more details"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
locking/lockdep: increase size of counters for lockdep statistics
locking/atomics: Use sed(1) instead of non-standard head(1) option
locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
x86/jump_label: Make tp_vec_nr static
x86/percpu: Optimize raw_cpu_xchg()
x86/percpu, sched/fair: Avoid local_clock()
x86/percpu, x86/irq: Relax {set,get}_irq_regs()
x86/percpu: Relax smp_processor_id()
x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
locking/rwsem: Guard against making count negative
locking/rwsem: Adaptive disabling of reader optimistic spinning
locking/rwsem: Enable time-based spinning on reader-owned rwsem
locking/rwsem: Make rwsem->owner an atomic_long_t
locking/rwsem: Enable readers spinning on writer
locking/rwsem: Clarify usage of owner's nonspinaable bit
locking/rwsem: Wake up almost all readers in wait queue
locking/rwsem: More optimal RT task handling of null owner
locking/rwsem: Always release wait_lock before waking up tasks
locking/rwsem: Implement lock handoff to prevent lock starvation
locking/rwsem: Make rwsem_spin_on_owner() return owner state
...
- Fix xarray entry association for mixed mappings
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Merge tag 'dax-fix-5.2-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull dax fix from Dan Williams:
"A single dax fix that has been soaking awaiting other fixes under
discussion to join it. As it is getting late in the cycle lets proceed
with this fix and save follow-on changes for post-v5.3-rc1.
- Fix xarray entry association for mixed mappings"
* tag 'dax-fix-5.2-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
dax: Fix xarray entry association for mixed mappings
All callers of lockdep_assert_held_exclusive() use it to verify the
correct locking state of either a semaphore (ldisc_sem in tty,
mmap_sem for perf events, i_rwsem of inode for dax) or rwlock by
apparmor. Thus it makes sense to rename _exclusive to _write since
that's the semantics callers care. Additionally there is already
lockdep_assert_held_read(), which this new naming is more consistent with.
No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190531100651.3969-1-nborisov@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When inserting entry into xarray, we store mapping and index in
corresponding struct pages for memory error handling. When it happened
that one process was mapping file at PMD granularity while another
process at PTE granularity, we could wrongly deassociate PMD range and
then reassociate PTE range leaving the rest of struct pages in PMD range
without mapping information which could later cause missed notifications
about memory errors. Fix the problem by calling the association /
deassociation code if and only if we are really going to update the
xarray (deassociating and associating zero or empty entries is just
no-op so there's no reason to complicate the code with trying to avoid
the calls for these cases).
Cc: <stable@vger.kernel.org>
Fixes: d2c997c0f1 ("fs, dax: use page->mapping to warn if truncate...")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms and conditions of the gnu general public license
version 2 as published by the free software foundation this program
is distributed in the hope it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 263 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.208660670@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
MADV_DONTNEED is handled with mmap_sem taken in read mode. We call
page_mkclean without holding mmap_sem.
MADV_DONTNEED implies that pages in the region are unmapped and subsequent
access to the pages in that range is handled as a new page fault. This
implies that if we don't have parallel access to the region when
MADV_DONTNEED is run we expect those range to be unallocated.
w.r.t page_mkclean() we need to make sure that we don't break the
MADV_DONTNEED semantics. MADV_DONTNEED check for pmd_none without holding
pmd_lock. This implies we skip the pmd if we temporarily mark pmd none.
Avoid doing that while marking the page clean.
Keep the sequence same for dax too even though we don't support
MADV_DONTNEED for dax mapping
The bug was noticed by code review and I didn't observe any failures w.r.t
test run. This is similar to
commit 58ceeb6bec
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date: Thu Apr 13 14:56:26 2017 -0700
thp: fix MADV_DONTNEED vs. MADV_FREE race
commit ced108037c
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date: Thu Apr 13 14:56:20 2017 -0700
thp: fix MADV_DONTNEED vs. numa balancing race
Link: http://lkml.kernel.org/r/20190321040610.14226-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc:"Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Architectures like ppc64 use the deposited page table to store hardware
page table slot information. Make sure we deposit a page table when
using zero page at the pmd level for hash.
Without this we hit
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc000000000082a74
Oops: Kernel access of bad area, sig: 11 [#1]
....
NIP [c000000000082a74] __hash_page_thp+0x224/0x5b0
LR [c0000000000829a4] __hash_page_thp+0x154/0x5b0
Call Trace:
hash_page_mm+0x43c/0x740
do_hash_page+0x2c/0x3c
copy_from_iter_flushcache+0xa4/0x4a0
pmem_copy_from_iter+0x2c/0x50 [nd_pmem]
dax_copy_from_iter+0x40/0x70
dax_iomap_actor+0x134/0x360
iomap_apply+0xfc/0x1b0
dax_iomap_rw+0xac/0x130
ext4_file_write_iter+0x254/0x460 [ext4]
__vfs_write+0x120/0x1e0
vfs_write+0xd8/0x220
SyS_write+0x6c/0x110
system_call+0x3c/0x130
Fixes: b5beae5e22 ("powerpc/pseries: Add driver for PAPR SCM regions")
Cc: <stable@vger.kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The radix tree would rewind the index in an iterator to the lowest index
of a multi-slot entry. The XArray iterators instead leave the index
unchanged, but I overlooked that when converting DAX from the radix tree
to the XArray. Adjust the index that we use for flushing to the start
of the PMD range.
Fixes: c1901cd33c ("page cache: Convert find_get_entries_tag to XArray")
Cc: <stable@vger.kernel.org>
Reported-by: Piotr Balcer <piotr.balcer@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Fixes: ac46d4f3c4 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This code is converted to use vmf_error().
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* Clean up unnecessary usage of prepare_to_wait_exclusive()
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Merge tag 'dax-fix-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull dax fix from Dan Williams:
"Clean up unnecessary usage of prepare_to_wait_exclusive().
While I feel a bit silly sending a single-commit pull-request there is
nothing else queued up for dax this cycle. This change has shipped in
-next for multiple releases"
* tag 'dax-fix-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
dax: Use non-exclusive wait in wait_entry_unlocked()
To avoid having to change many call sites everytime we want to add a
parameter use a structure to group all parameters for the mmu_notifier
invalidate_range_start/end cakks. No functional changes with this patch.
[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20181205053628.3210-3-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
From: Jérôme Glisse <jglisse@redhat.com>
Subject: mm/mmu_notifier: use structure for invalidate_range_start/end calls v3
fix build warning in migrate.c when CONFIG_MMU_NOTIFIER=n
Link: http://lkml.kernel.org/r/20181213171330.8489-3-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_unlocked_entry() uses an exclusive wait because it is guaranteed to
eventually obtain the lock and follow on with an unlock+wakeup cycle.
The wait_entry_unlocked() path does not have the same guarantee. Rather
than open-code an extra wakeup, just switch to a non-exclusive wait.
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Internal to dax_unlock_mapping_entry(), dax_unlock_entry() is used to
store a replacement entry in the Xarray at the given xas-index with the
DAX_LOCKED bit clear. When called, dax_unlock_entry() expects the unlocked
value of the entry relative to the current Xarray state to be specified.
In most contexts dax_unlock_entry() is operating in the same scope as
the matched dax_lock_entry(). However, in the dax_unlock_mapping_entry()
case the implementation needs to recall the original entry. In the case
where the original entry is a 'pmd' entry it is possible that the pfn
performed to do the lookup is misaligned to the value retrieved in the
Xarray.
Change the api to return the unlock cookie from dax_lock_page() and pass
it to dax_unlock_page(). This fixes a bug where dax_unlock_page() was
assuming that the page was PMD-aligned if the entry was a PMD entry with
signatures like:
WARNING: CPU: 38 PID: 1396 at fs/dax.c:340 dax_insert_entry+0x2b2/0x2d0
RIP: 0010:dax_insert_entry+0x2b2/0x2d0
[..]
Call Trace:
dax_iomap_pte_fault.isra.41+0x791/0xde0
ext4_dax_huge_fault+0x16f/0x1f0
? up_read+0x1c/0xa0
__do_fault+0x1f/0x160
__handle_mm_fault+0x1033/0x1490
handle_mm_fault+0x18b/0x3d0
Link: https://lkml.kernel.org/r/20181130154902.GL10377@bombadil.infradead.org
Fixes: 9f32d22130 ("dax: Convert dax_lock_mapping_entry to XArray")
Reported-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
After we drop the i_pages lock, the inode can be freed at any time.
The get_unlocked_entry() code has no choice but to reacquire the lock,
so it can't be used here. Create a new wait_entry_unlocked() which takes
care not to acquire the lock or dereference the address_space in any way.
Fixes: c2a7d2a115 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Cc: <stable@vger.kernel.org>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
If we race with inode destroy, it's possible for page->mapping to be
NULL before we even enter this routine, as well as after having slept
waiting for the dax entry to become unlocked.
Fixes: c2a7d2a115 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Cc: <stable@vger.kernel.org>
Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
After calling get_unlocked_entry(), you have to call
put_unlocked_entry() to avoid subsequent waiters losing wakeups.
Fixes: c2a7d2a115 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Using xas_load() with a PMD-sized xa_state would work if either a
PMD-sized entry was present or a PTE sized entry was present in the
first 64 entries (of the 512 PTEs in a PMD on x86). If there was no
PTE in the first 64 entries, grab_mapping_entry() would believe there
were no entries present, allocate a PMD-sized entry and overwrite the
PTE in the page cache.
Use xas_find_conflict() instead which turns out to simplify
both get_unlocked_entry() and grab_mapping_entry(). Also remove a
WARN_ON_ONCE from grab_mapping_entry() as it will have already triggered
in get_unlocked_entry().
Fixes: cfc93c6c6c ("dax: Convert dax_insert_pfn_mkwrite to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Device DAX PMD pages do not set the PageHead bit for compound pages.
Fix for now by retrieving the PMD bit from the entry, but eventually we
will be passed the page size by the caller.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Fixes: 9f32d22130 ("dax: Convert dax_lock_mapping_entry to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
For the device-dax case, it is possible that the inode can go away
underneath us. The rcu_read_lock() was there to prevent it from
being freed, and not (as I thought) to protect the tree. Bring back
the rcu_read_lock() protection. Also add a little kernel-doc; while
this function is not exported to modules, it is used from outside dax.c
Reported-by: Dan Williams <dan.j.williams@intel.com>
Fixes: 9f32d22130 ("dax: Convert dax_lock_mapping_entry to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
I wrote the semantics in the commit message, but didn't document it in
the source code. Use a BUG_ON instead (if any code does do this, it's
really buggy; we can't recover and it's worth taking the machine down).
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Skipping some of the revalidation after we sleep can lead to returning
a mapping which has already been freed. Just drop this optimisation.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Fixes: 9f32d22130 ("dax: Convert dax_lock_mapping_entry to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Instead of using a pagevec, just use the XArray iterators. Add a
conditional rescheduling point which probably should have been there in
the original.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Add some XArray-based helper functions to replace the radix tree based
metaphors currently in use. The biggest change is that converted code
doesn't see its own lock bit; get_unlocked_entry() always returns an
entry with the lock bit clear. So we don't have to mess around loading
the current entry and clearing the lock bit; we can just store the
unlocked entry that we already have.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Since the XArray is embedded in the struct address_space, its address
contains exactly as much entropy as the address of the mapping. This
patch is purely preparatory for later patches which will simplify the
wait/wake interfaces.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Introduce xarray value entries and tagged pointers to replace radix
tree exceptional entries. This is a slight change in encoding to allow
the use of an extra bit (we can now store BITS_PER_LONG - 1 bits in a
value entry). It is also a change in emphasis; exceptional entries are
intimidating and different. As the comment explains, you can choose
to store values or pointers in the xarray and they are both first-class
citizens.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Use my_zero_pfn instead of ZERO_PAGE(), and pass the vaddr to it instead
of zero so it works on MIPS and s390 who reference the vaddr to select a
zero page.
Cc: <stable@vger.kernel.org>
Fixes: 91d25ba8a6 ("dax: use common 4k zero page for dax mmap reads")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* memory_failure() gets confused by dev_pagemap backed mappings. The
recovery code has specific enabling for several possible page states
that needs new enabling to handle poison in dax mappings. Teach
memory_failure() about ZONE_DEVICE pages.
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Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm memory-failure update from Dave Jiang:
"As it stands, memory_failure() gets thoroughly confused by dev_pagemap
backed mappings. The recovery code has specific enabling for several
possible page states and needs new enabling to handle poison in dax
mappings.
In order to support reliable reverse mapping of user space addresses:
1/ Add new locking in the memory_failure() rmap path to prevent races
that would typically be handled by the page lock.
2/ Since dev_pagemap pages are hidden from the page allocator and the
"compound page" accounting machinery, add a mechanism to determine
the size of the mapping that encompasses a given poisoned pfn.
3/ Given pmem errors can be repaired, change the speculatively
accessed poison protection, mce_unmap_kpfn(), to be reversible and
otherwise allow ongoing access from the kernel.
A side effect of this enabling is that MADV_HWPOISON becomes usable
for dax mappings, however the primary motivation is to allow the
system to survive userspace consumption of hardware-poison via dax.
Specifically the current behavior is:
mce: Uncorrected hardware memory error in user-access at af34214200
{1}[Hardware Error]: It has been corrected by h/w and requires no further action
mce: [Hardware Error]: Machine check events logged
{1}[Hardware Error]: event severity: corrected
Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users
[..]
Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed
mce: Memory error not recovered
<reboot>
...and with these changes:
Injecting memory failure for pfn 0x20cb00 at process virtual address 0x7f763dd00000
Memory failure: 0x20cb00: Killing dax-pmd:5421 due to hardware memory corruption
Memory failure: 0x20cb00: recovery action for dax page: Recovered
Given all the cross dependencies I propose taking this through
nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax
folks"
* tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm:
libnvdimm, pmem: Restore page attributes when clearing errors
x86/memory_failure: Introduce {set, clear}_mce_nospec()
x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses
mm, memory_failure: Teach memory_failure() about dev_pagemap pages
filesystem-dax: Introduce dax_lock_mapping_entry()
mm, memory_failure: Collect mapping size in collect_procs()
mm, madvise_inject_error: Let memory_failure() optionally take a page reference
mm, dev_pagemap: Do not clear ->mapping on final put
mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages
filesystem-dax: Set page->index
device-dax: Set page->index
device-dax: Enable page_mapping()
device-dax: Convert to vmf_insert_mixed and vm_fault_t
Collection of misc libnvdimm patches for 4.19 submission
* Adding support to read locked nvdimm capacity.
* Change test code to make DSM failure code injection an override.
* Add support for calculate maximum contiguous area for namespace.
* Add support for queueing a short ARS when there is on going ARS for
nvdimm.
* Allow NULL to be passed in to ->direct_access() for kaddr and
pfn params.
* Improve smart injection support for nvdimm emulation testing.
* Fix test code that supports for emulating controller temperature.
* Fix hang on error before devm_memremap_pages()
* Fix a bug that causes user memory corruption when data returned
to user for ars_status.
* Maintainer updates for Ross Zwisler emails and adding Jan Kara to fsdax.
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Merge tag 'libnvdimm-for-4.19_misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm updates from Dave Jiang:
"Collection of misc libnvdimm patches for 4.19 submission:
- Adding support to read locked nvdimm capacity.
- Change test code to make DSM failure code injection an override.
- Add support for calculate maximum contiguous area for namespace.
- Add support for queueing a short ARS when there is on going ARS for
nvdimm.
- Allow NULL to be passed in to ->direct_access() for kaddr and pfn
params.
- Improve smart injection support for nvdimm emulation testing.
- Fix test code that supports for emulating controller temperature.
- Fix hang on error before devm_memremap_pages()
- Fix a bug that causes user memory corruption when data returned to
user for ars_status.
- Maintainer updates for Ross Zwisler emails and adding Jan Kara to
fsdax"
* tag 'libnvdimm-for-4.19_misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm:
libnvdimm: fix ars_status output length calculation
device-dax: avoid hang on error before devm_memremap_pages()
tools/testing/nvdimm: improve emulation of smart injection
filesystem-dax: Do not request kaddr and pfn when not required
md/dm-writecache: Don't request pointer dummy_addr when not required
dax/super: Do not request a pointer kaddr when not required
tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()
s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()
acpi/nfit: queue issuing of ars when an uc error notification comes in
libnvdimm: Export max available extent
libnvdimm: Use max contiguous area for namespace size
MAINTAINERS: Add Jan Kara for filesystem DAX
MAINTAINERS: update Ross Zwisler's email address
tools/testing/nvdimm: Fix support for emulating controller temperature
tools/testing/nvdimm: Make DSM failure code injection an override
acpi, nfit: Prefer _DSM over _LSR for namespace label reads
libnvdimm: Introduce locked DIMM capacity support
Some functions within fs/dax don't need to get local pointer kaddr
or variable pfn from direct_access. Using NULL instead of having to
pass in useless pointer or variable that caller then just throw away.
Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Inodes using DAX should only ever have exceptional entries in their page
caches. Make this clear by warning if the iteration in
dax_layout_busy_page() ever sees a non-exceptional entry, and by adding a
comment for the pagevec_release() call which only deals with struct page
pointers.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
In preparation for implementing support for memory poison (media error)
handling via dax mappings, implement a lock_page() equivalent. Poison
error handling requires rmap and needs guarantees that the page->mapping
association is maintained / valid (inode not freed) for the duration of
the lookup.
In the device-dax case it is sufficient to simply hold a dev_pagemap
reference. In the filesystem-dax case we need to use the entry lock.
Export the entry lock via dax_lock_mapping_entry() that uses
rcu_read_lock() to protect against the inode being freed, and
revalidates the page->mapping association under xa_lock().
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
In support of enabling memory_failure() handling for filesystem-dax
mappings, set ->index to the pgoff of the page. The rmap implementation
requires ->index to bound the search through the vma interval tree. The
index is set and cleared at dax_associate_entry() and
dax_disassociate_entry() time respectively.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Jan Kara