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If dma_fence_chain_find_seqno() reports an error, it does so in its
preamble before it disposes of the input fence. On handling the
error, we need to drop the reference to the fence.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2292
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: 13149e8bafc4 ("drm/i915: add syncobj timeline support")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200806161056.17593-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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As we now protect the timeline list using RCU, we can drop the
timeline->mutex for guarding the list iteration during context close, as
we are searching for an inflight request. Any new request will see the
context is banned and not be submitted. In doing so, pull the checks for
a concurrent submission of the request (notably the
i915_request_completed()) under the engine spinlock, to fully serialise
with __i915_request_submit()). That is in the case of preempt-to-busy
where the request may be completed during the __i915_request_submit(),
we need to be careful that we sample the request status after
serialising so that we don't miss the request the engine is actually
submitting.
Fixes: 4a3174152147 ("drm/i915/gem: Refine occupancy test in kill_context()")
References: d22d2d073ef8 ("drm/i915: Protect i915_request_await_start from early waits") # rcu protection of timeline->requests
References: https://gitlab.freedesktop.org/drm/intel/-/issues/1622
References: https://gitlab.freedesktop.org/drm/intel/-/issues/2158
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200806105954.7766-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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The GEM object is grossly overweight for the practicality of tracking
large numbers of individual pages, yet it is currently our only
abstraction for tracking DMA allocations. Since those allocations need
to be reserved upfront before an operation, and that we need to break
away from simple system memory, we need to ditch using plain struct page
wrappers.
In the process, we drop the WC mapping as we ended up clflushing
everything anyway due to various issues across a wider range of
platforms. Though in a future step, we need to drop the kmap_atomic
approach which suggests we need to pre-map all the pages and keep them
mapped.
v2: Verify our large scratch page is suitably DMA aligned; and manually
clear the scratch since we are allocating plain struct pages full of
prior content.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200729164219.5737-2-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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We need to make the DMA allocations used for page directories to be
performed up front so that we can include those allocations in our
memory reservation pass. The downside is that we have to assume the
worst case, even before we know the final layout, and always allocate
enough page directories for this object, even when there will be overlap.
This unfortunately can be quite expensive, especially as we have to
clear/reset the page directories and DMA pages, but it should only be
required during early phases of a workload when new objects are being
discovered, or after memory/eviction pressure when we need to rebind.
Once we reach steady state, the objects should not be moved and we no
longer need to preallocating the pages tables.
It should be noted that the lifetime for the page directories DMA is
more or less decoupled from individual fences as they will be shared
across objects across timelines.
v2: Only allocate enough PD space for the PTE we may use, we do not need
to allocate PD that will be left as scratch.
v3: Store the shift unto the first PD level to encapsulate the different
PTE counts for gen6/gen8.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200729164219.5737-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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Sometimes we have to be very careful not to allocate underneath a mutex
(or spinlock) and yet still want to track activity. Enter
i915_active_acquire_for_context(). This raises the activity counter on
i915_active prior to use and ensures that the fence-tree contains a slot
for the context.
v2: Refactor active_lookup() so it can be called again before/after
locking to resolve contention. Since we protect the rbtree until we
idle, we can do a lockfree lookup, with the caveat that if another
thread performs a concurrent insertion, the rotations from the insert
may cause us to not find our target. A second pass holding the treelock
will find the target if it exists, or the place to perform our
insertion.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731085015.32368-3-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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We may need to allocate more than one pinned context/timeline for each
engine which can utilise the per-engine HWSP, so we need to give each
a different offset within it.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730183906.25422-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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Avoid exposing a partially constructed context by deferring the
list_add() from the initial construction to the end of registration.
Otherwise, if we peek into the list of contexts from inside debugfs, we
may see the partially constructed context and chase down some dangling
incomplete pointers.
Reported-by: CQ Tang <cq.tang@intel.com>
Fixes: 3aa9945a528e ("drm/i915: Separate GEM context construction and registration to userspace")
References: f6e8aa387171 ("drm/i915: Report the number of closed vma held by each context in debugfs")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: CQ Tang <cq.tang@intel.com>
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730092856.23615-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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I915_GEM_THROTTLE dates back to the time before contexts where there was
just a single engine, and therefore a single timeline and request list
globally. That request list was in execution/retirement order, and so
walking it to find a particular aged request made sense and could be
split per file.
That is no more. We now have many timelines with a file, as many as the
user wants to construct (essentially per-engine, per-context). Each of
those run independently and so make the single list futile. Remove the
disordered list, and iterate over all the timelines to find a request to
wait on in each to satisfy the criteria that the CPU is no more than 20ms
ahead of its oldest request.
It should go without saying that the I915_GEM_THROTTLE ioctl is no
longer used as the primary means of throttling, so it makes sense to push
the complication into the ioctl where it only impacts upon its few
irregular users, rather than the execbuf/retire where everybody has to
pay the cost. Fortunately, the few users do not create vast amount of
contexts, so the loops over contexts/engines should be concise.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200728152010.30701-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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Merge emailed patches from Peter Xu:
"This is a small series that I picked up from Linus's suggestion to
simplify cow handling (and also make it more strict) by checking
against page refcounts rather than mapcounts.
This makes uffd-wp work again (verified by running upmapsort)"
Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:
8 files changed, 29 insertions(+), 120 deletions(-)
The reason for the bad timing is that it turns out that commit
17839856fd58 ("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.
And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.
Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/
* emailed patches from Peter Xu <peterx@redhat.com>:
mm: Add PGREUSE counter
mm/gup: Remove enfornced COW mechanism
mm/ksm: Remove reuse_ksm_page()
mm: do_wp_page() simplification
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With the more strict (but greatly simplified) page reuse logic in
do_wp_page(), we can safely go back to the world where cow is not
enforced with writes.
This essentially reverts commit 17839856fd58 ("gup: document and work
around 'COW can break either way' issue"). There are some context
differences due to some changes later on around it:
2170ecfa7688 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03)
376a34efa4ee ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03)
Some lines moved back and forth with those, but this revert patch should
have striped out and covered all the enforced cow bits anyways.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://anongit.freedesktop.org/drm/drm-intel into drm-next
UAPI Changes:
- Introduce a mechanism to extend execbuf2 (Lionel)
- Add syncobj timeline support (Lionel)
Driver Changes:
- Limit stolen mem usage on the compressed frame buffer (Ville)
- Some clean-up around display's cdclk (Ville)
- Some DDI changes for better DP link training according
to spec (Imre)
- Provide the perf pmu.module (Chris)
- Remove dobious Valleyview PCI IDs (Alexei)
- Add new display power saving feature for gen12+ called
HOBL (Jose)
- Move SKL's clock gating w/a to skl_init_clock_gating() (Ville)
- Rocket Lake display additions (Matt)
- Selftest: temporarily downgrade on severity of frequency
scaling tests (Chris)
- Introduce a new display workaround for fixing FLR related
issues on new PCH. (Jose)
- Temporarily disable FBC on TGL. It was the culprit of random
underruns. (Uma).
- Copy default modparams to mock i915_device (Chris)
- Add compiler paranoia for checking HWSP values (Chris)
- Remove useless gen check before calling intel_rps_boost (Chris)
- Fix a null pointer dereference (Chris)
- Add a couple of missing i915_active_fini() (Chris)
- Update TGL display power's bw_buddy table according to
update spec (Matt)
- Fix couple wrong return values (Tianjia)
- Selftest: Avoid passing random 0 into ilog2 (George)
- Many Tiger Lake display fixes and improvements for Type-C and
DP compliance (Imre, Jose)
- Start the addition of PSR2 selective fetch (Jose)
- Update a few DMC and HuC firmware versions (Jose)
- Add gen11+ w/a to fix underuns (Matt)
- Fix cmd parser desc matching with mask (Mika)
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200826232733.GA129053@intel.com
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Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.
[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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Introduces a new parameters to execbuf so that we can specify syncobj
handles as well as timeline points.
v2: Reuse i915_user_extension_fn
v3: Check that the chained extension is only present once (Chris)
v4: Check that dma_fence_chain_find_seqno returns a non NULL fence (Lionel)
v5: Use BIT_ULL (Chris)
v6: Fix issue with already signaled timeline points,
dma_fence_chain_find_seqno() setting fence to NULL (Chris)
v7: Report ENOENT with invalid syncobj handle (Lionel)
v8: Check for out of order timeline point insertion (Chris)
v9: After explanations on
https://lists.freedesktop.org/archives/dri-devel/2019-August/229287.html
drop the ordering check from v8 (Lionel)
v10: Set first extension enum item to 1 (Jason)
v11: Rebase
v12: Allow multiple extension nodes of timeline syncobj (Chris)
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Co-authored-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v11)
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804085954.350343-3-lionel.g.landwerlin@intel.com
Link: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2901
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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We're planning to use this for a couple of new feature where we need
to provide additional parameters to execbuf.
v2: Check for invalid flags in execbuffer2 (Lionel)
v3: Rename I915_EXEC_EXT -> I915_EXEC_USE_EXTENSIONS (Chris)
v4: Rebase
Move array fence parsing in i915_gem_do_execbuffer()
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804085954.350343-2-lionel.g.landwerlin@intel.com
Link: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2901
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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After the cleanup of page fault accounting, gup does not need to pass
task_struct around any more. Remove that parameter in the whole gup
stack.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Last user removed, remove the get_dirty_page convenience function.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708173748.32734-4-chris@chris-wilson.co.uk
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Some objects we map once during their construction, and then never
access their mappings again, even if they are kept around for the
duration of the driver. Keeping those pages mapped, often vmapped, is
therefore wasteful and we should release the maps as soon as we no
longer need them.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708173748.32734-3-chris@chris-wilson.co.uk
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We removed retiring requests from the shrinker in order to decouple the
mutexes from reclaim in preparation for unravelling the struct_mutex.
The impact of not retiring is that we are much less agressive in making
global objects available for shrinking, as such objects remain pinned
until they are flushed by a heartbeat pulse following the last retired
request along their timeline. In order to ensure that pulse occurs in
time for memory reclamation, we should kick it from kswapd.
The catch is that we have added some flush_work() into the retirement
phase (to ensure that we reach a global idle in a timely manner), but
these flush_work() are not eligible (i.e do not belong to WQ_MEM_RELCAIM)
for use from inside kswapd. To avoid flushing those workqueues, we teach
the retirer not to do so unless we are actually waiting, and only do the
plain retire from inside the shrinker.
Note that for execlists, we already retire completed contexts as they
are scheduled out, so it should not be keeping global state
unnecessarily pinned. The legacy ringbuffer however...
References: 9e9539800dd4 ("drm/i915: Remove waiting & retiring from shrinker paths")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708173748.32734-1-chris@chris-wilson.co.uk
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SSEUs are a GT capability, so track them under gt_info.
Signed-off-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708003952.21831-8-daniele.ceraolospurio@intel.com
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Since the engines belong to the GT, move the runtime-updated list of
available engines to the intel_gt struct. The original mask has been
renamed to indicate it contains the maximum engine list that can be
found on a matching device.
In preparation for other info being moved to the gt in follow up patches
(sseu), introduce an intel_gt_info structure to group all gt-related
runtime info.
v2: s/max_engine_mask/platform_engine_mask (tvrtko), fix selftest
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> #v1
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200708003952.21831-5-daniele.ceraolospurio@intel.com
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Reuse the ppgtt_bind_vma() for aliasing_ppgtt_bind_vma() so we can
reduce some code near-duplication. The catch is that we need to then
pass along the i915_address_space and not rely on vma->vm, as they
differ with the aliasing-ppgtt.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703102519.26539-1-chris@chris-wilson.co.uk
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Rather than reuse the common ctx->mutex for locking the execbuffer LUT,
split it into its own lock to avoid being taken [as part of ctx->mutex]
at inappropriate times. In particular to avoid the inversion from taking
the timeline->mutex for the whole execbuf submission in the next patch.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703004306.11117-1-chris@chris-wilson.co.uk
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Since we no longer always take struct_mutex around everything, and want
the freedom to create GEM objects, actually taking struct_mutex inside
the lock creation ends up pulling the mutex inside other looks. Since we
don't use generally use struct_mutex, we can relax the tainting.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200702083225.20044-3-chris@chris-wilson.co.uk
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Avoid waking up the device and taking stale locks if we know that the
object is not currently mmapped. This is particularly useful as not many
object are actually mmapped and so we can destroy them without waking
the device up, and gives us a little more freedom of workqueue ordering
during shutdown.
v2: Pull the release_mmap() into its single user in freeing the objects,
where there can not be any race with a concurrent user of the freed
object. Or so one hopes!
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Link: https://patchwork.freedesktop.org/patch/msgid/20200702163623.6402-2-chris@chris-wilson.co.uk
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Only a GGTT mmapping will use the aperture detiling registers, so on a
tiling change for an object, we only need to revoke those mmappings and
not the CPU mmappings (which are always linear irrespective of the tiling).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200702163623.6402-1-chris@chris-wilson.co.uk
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The obj->lut_list is traversed when the object is closed as the file
table is destroyed during process termination. As this occurs before we
kill any outstanding context if, due to some bug or another, the closure
is blocked, then we fail to shootdown any inflight operations
potentially leaving the GPU spinning forever. As we only need to guard
the list against concurrent closures and insertions, the hold is short
and merits being treated as a simple spinlock.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701084439.17025-1-chris@chris-wilson.co.uk
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Rearrange the allocation of the mm_struct registration to avoid
allocating underneath the i915->mm_lock, so that we avoid tainting the
lock (and in turn many other locks that may be held as i915->mm_lock is
taken, and those locks we may want on the free [shrinker] paths). In
doing so, we convert the lookup to be RCU protected by courtesy of
converting the free-worker to be an rcu_work.
v2: Remember to use hash_rcu variants to protect the list iteration from
concurrent add/del.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200619194038.5088-1-chris@chris-wilson.co.uk
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Catch up with upstream, in particular to get c1e8d7c6a7a6 ("mmap locking
API: convert mmap_sem comments").
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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Start using device specific parameters instead of module parameters for
most things. The module parameters become the immutable initial values
for i915 parameters. The device specific parameters in i915->params
start life as a copy of i915_modparams. Any later changes are only
reflected in the debugfs.
The stragglers are:
* i915.force_probe and i915.modeset. Needed before dev_priv is
available. This is fine because the parameters are read-only and never
modified.
* i915.verbose_state_checks. Passing dev_priv to I915_STATE_WARN and
I915_STATE_WARN_ON would result in massive and ugly churn. This is
handled by not exposing the parameter via debugfs, and leaving the
parameter writable in sysfs. This may be fixed up in follow-up work.
* i915.inject_probe_failure. Only makes sense in terms of the module,
not the device. This is handled by not exposing the parameter via
debugfs.
v2: Fix uc i915 lookup code (Michał Winiarski)
Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila@intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200618150402.14022-1-jani.nikula@intel.com
|
|
One i915_request_await_object is enough and we keep the one under the
object lock so it is final.
At the same time move async clflushing setup under the same locked
section and consolidate common code into a helper function.
v2:
* Emit initial breadcrumbs after aways are set up. (Chris)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200615151449.32605-1-tvrtko.ursulin@linux.intel.com
|
|
Pull drm fixes from Dave Airlie:
"One sun4i fix and a connector hotplug race The ast fix is for a
regression in 5.6, and one of the i915 ones fixes an oops reported by
dhowells.
core:
- fix race in connectors sending hotplug
i915:
- Avoid use after free in cmdparser
- Avoid NULL dereference when probing all display encoders
- Fixup to module parameter type
sun4i:
- clock divider fix
ast:
- 24/32 bpp mode setting fix"
* tag 'drm-next-2020-06-11-1' of git://anongit.freedesktop.org/drm/drm:
drm/ast: fix missing break in switch statement for format->cpp[0] case 4
drm/sun4i: hdmi ddc clk: Fix size of m divider
drm/i915/display: Only query DP state of a DDI encoder
drm/i915/params: fix i915.reset module param type
drm/i915/gem: Mark the buffer pool as active for the cmdparser
drm/connector: notify userspace on hotplug after register complete
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull i915 uaccess updates from Al Viro:
"Low-hanging fruit in i915; there are several trickier followups, but
that'll wait for the next cycle"
* 'uaccess.i915' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
i915:get_engines(): get rid of pointless access_ok()
i915: alloc_oa_regs(): get rid of pointless access_ok()
i915 compat ioctl(): just use drm_ioctl_kernel()
i915: switch copy_perf_config_registers_or_number() to unsafe_put_user()
i915: switch query_{topology,engine}_info() to copy_to_user()
|
|
Convert comments that reference mmap_sem to reference mmap_lock instead.
[akpm@linux-foundation.org: fix up linux-next leftovers]
[akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil]
[akpm@linux-foundation.org: more linux-next fixups, per Michel]
Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.
The change is generated using coccinelle with the following rule:
// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .
@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)
Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Pull drm fixes from Dave Airlie:
"These are the fixes from last week for the stuff merged in the merge
window. It got a bunch of nouveau fixes for HDA audio on some new
GPUs, some i915 and some amdpgu fixes.
i915:
- gvt: Fix one clang warning on debug only function
- Use ARRAY_SIZE for coccicheck warning
- Use after free fix for display global state.
- Whitelisting context-local timestamp on Gen9 and two scheduler
fixes with deps (Cc: stable)
- Removal of write flag from sysfs files where ineffective
nouveau:
- HDMI/DP audio HDA fixes
- display hang fix for Volta/Turing
- GK20A regression fix.
amdgpu:
- Prevent hwmon accesses while GPU is in reset
- CTF interrupt fix
- Backlight fix for renoir
- Fix for display sync groups
- Display bandwidth validation workaround"
* tag 'drm-next-2020-06-08' of git://anongit.freedesktop.org/drm/drm: (28 commits)
drm/nouveau/kms/nv50-: clear SW state of disabled windows harder
drm/nouveau: gr/gk20a: Use firmware version 0
drm/nouveau/disp/gm200-: detect and potentially disable HDA support on some SORs
drm/nouveau/disp/gp100: split SOR implementation from gm200
drm/nouveau/disp: modify OR allocation policy to account for HDA requirements
drm/nouveau/disp: split part of OR allocation logic into a function
drm/nouveau/disp: provide hint to OR allocation about HDA requirements
drm/amd/display: Revalidate bandwidth before commiting DC updates
drm/amdgpu/display: use blanked rather than plane state for sync groups
drm/i915/params: fix i915.fake_lmem_start module param sysfs permissions
drm/i915/params: don't expose inject_probe_failure in debugfs
drm/i915: Whitelist context-local timestamp in the gen9 cmdparser
drm/i915: Fix global state use-after-frees with a refcount
drm/i915: Check for awaits on still currently executing requests
drm/i915/gt: Do not schedule normal requests immediately along virtual
drm/i915: Reorder await_execution before await_request
drm/nouveau/kms/gt215-: fix race with audio driver runpm
drm/nouveau/disp/gm200-: fix NV_PDISP_SOR_HDMI2_CTRL(n) selection
Revert "drm/amd/display: disable dcn20 abm feature for bring up"
drm/amd/powerplay: ack the SMUToHost interrupt on receive V2
...
|
|
If the execbuf is interrupted after building the cmdparser pipeline, and
before we commit to submitting the request to HW, we would attempt to
clean up the cmdparser early. While we held active references to the vma
being parsed and constructed, we did not hold an active reference for
the buffer pool itself. The result was that an interrupted execbuf could
still have run the cmdparser pipeline, but since the buffer pool was
idle, its target vma could have been recycled.
Note this problem only occurs if the cmdparser is running async due to
pipelined waits on busy fences, and the execbuf is interrupted.
Fixes: 686c7c35abc2 ("drm/i915/gem: Asynchronous cmdparser")
Fixes: 16e87459673a ("drm/i915/gt: Move the batch buffer pool from the engine to the gt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604103751.18816-1-chris@chris-wilson.co.uk
(cherry picked from commit 57a78ca4eceab1ecb0299fba8a10211289329889)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
|
|
git://anongit.freedesktop.org/drm/drm-intel into drm-next
- Includes gvt-next-fixes-2020-05-28
- Use after free fix for display global state.
- Whitelisting context-local timestamp on Gen9
and two scheduler fixes with deps (Cc: stable)
- Removal of write flag from sysfs files where
ineffective
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604150454.GA59322@jlahtine-desk.ger.corp.intel.com
|
|
Unused as of commit 9e0f9464e2ab ("drm/i915/gem: Async GPU relocations
only"), but left behind.
>> drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:933:21: error: unused function 'unmask_page' [-Werror,-Wunused-function]
static inline void *unmask_page(unsigned long p)
^
>> drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:938:28: error: unused function 'unmask_flags' [-Werror,-Wunused-function]
static inline unsigned int unmask_flags(unsigned long p)
^
>> drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:945:33: error: unused function 'cache_to_ggtt' [-Werror,-Wunused-function]
static inline struct i915_ggtt *cache_to_ggtt(struct reloc_cache *cache)
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200605200357.13069-1-chris@chris-wilson.co.uk
|
|
Reduce the 3 relocation paths down to the single path that accommodates
all. The primary motivation for this is to guard the relocations with a
natural fence (derived from the i915_request used to write the
relocation from the GPU).
The tradeoff in using async gpu relocations is that it increases latency
over using direct CPU relocations, for the cases where the target is
idle and accessible by the CPU. The benefit is greatly reduced lock
contention and improved concurrency by pipelining.
Note that forcing the async gpu relocations does reveal a few issues
they have. Firstly, is that they are visible as writes to gem_busy,
causing to mark some buffers are being to written to by the GPU even
though userspace only reads. Secondly is that, in combination with the
cmdparser, they can cause priority inversions. This should be the case
where the work is being put into a common workqueue losing our priority
information and so being executed in FIFO from the worker, denying us
the opportunity to reorder the requests afterwards.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604211457.19696-1-chris@chris-wilson.co.uk
|
|
If the execbuf is interrupted after building the cmdparser pipeline, and
before we commit to submitting the request to HW, we would attempt to
clean up the cmdparser early. While we held active references to the vma
being parsed and constructed, we did not hold an active reference for
the buffer pool itself. The result was that an interrupted execbuf could
still have run the cmdparser pipeline, but since the buffer pool was
idle, its target vma could have been recycled.
Note this problem only occurs if the cmdparser is running async due to
pipelined waits on busy fences, and the execbuf is interrupted.
Fixes: 686c7c35abc2 ("drm/i915/gem: Asynchronous cmdparser")
Fixes: 16e87459673a ("drm/i915/gt: Move the batch buffer pool from the engine to the gt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604103751.18816-1-chris@chris-wilson.co.uk
|
|
Just to remove an obnoxious HAS_ENGINES(), and in the process make the
code agnostic to the availabilty of any particular engine by making it
exercise any and all such engines declared on the system.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604123641.767-1-chris@chris-wilson.co.uk
|
|
This code was using get_user_pages*(), in a "Case 2" scenario (DMA/RDMA),
using the categorization from [1]. That means that it's time to convert
the get_user_pages*() + put_page() calls to pin_user_pages*() +
unpin_user_pages() calls.
There is some helpful background in [2]: basically, this is a small part
of fixing a long-standing disconnect between pinning pages, and file
systems' use of those pages.
[1] Documentation/core-api/pin_user_pages.rst
[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Link: http://lkml.kernel.org/r/20200519002124.2025955-5-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
We infrequently use the direct i915 backpointer from the i915_request,
so do we really need to waste the space in the struct for it? 8 bytes
from the most frequently allocated struct vs an 3 bytes and pointer
chasing in using rq->engine->i915?
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602220953.21178-1-chris@chris-wilson.co.uk
|
|
Pull drm updates from Dave Airlie:
"Highlights:
- Core DRM had a lot of refactoring around managed drm resources to
make drivers simpler.
- Intel Tigerlake support is on by default
- amdgpu now support p2p PCI buffer sharing and encrypted GPU memory
Details:
core:
- uapi: error out EBUSY when existing master
- uapi: rework SET/DROP MASTER permission handling
- remove drm_pci.h
- drm_pci* are now legacy
- introduced managed DRM resources
- subclassing support for drm_framebuffer
- simple encoder helper
- edid improvements
- vblank + writeback documentation improved
- drm/mm - optimise tree searches
- port drivers to use devm_drm_dev_alloc
dma-buf:
- add flag for p2p buffer support
mst:
- ACT timeout improvements
- remove drm_dp_mst_has_audio
- don't use 2nd TX slot - spec recommends against it
bridge:
- dw-hdmi various improvements
- chrontel ch7033 support
- fix stack issues with old gcc
hdmi:
- add unpack function for drm infoframe
fbdev:
- misc fbdev driver fixes
i915:
- uapi: global sseu pinning
- uapi: OA buffer polling
- uapi: remove generated perf code
- uapi: per-engine default property values in sysfs
- Tigerlake GEN12 enabled.
- Lots of gem refactoring
- Tigerlake enablement patches
- move to drm_device logging
- Icelake gamma HW readout
- push MST link retrain to hotplug work
- bandwidth atomic helpers
- ICL fixes
- RPS/GT refactoring
- Cherryview full-ppgtt support
- i915 locking guidelines documented
- require linear fb stride to be 512 multiple on gen9
- Tigerlake SAGV support
amdgpu:
- uapi: encrypted GPU memory handling
- uapi: add MEM_SYNC IB flag
- p2p dma-buf support
- export VRAM dma-bufs
- FRU chip access support
- RAS/SR-IOV updates
- Powerplay locking fixes
- VCN DPG (powergating) enablement
- GFX10 clockgating fixes
- DC fixes
- GPU reset fixes
- navi SDMA fix
- expose FP16 for modesetting
- DP 1.4 compliance fixes
- gfx10 soft recovery
- Improved Critical Thermal Faults handling
- resizable BAR on gmc10
amdkfd:
- uapi: GWS resource management
- track GPU memory per process
- report PCI domain in topology
radeon:
- safe reg list generator fixes
nouveau:
- HD audio fixes on recent systems
- vGPU detection (fail probe if we're on one, for now)
- Interlaced mode fixes (mostly avoidance on Turing, which doesn't support it)
- SVM improvements/fixes
- NVIDIA format modifier support
- Misc other fixes.
adv7511:
- HDMI SPDIF support
ast:
- allocate crtc state size
- fix double assignment
- fix suspend
bochs:
- drop connector register
cirrus:
- move to tiny drivers.
exynos:
- fix imported dma-buf mapping
- enable runtime PM
- fixes and cleanups
mediatek:
- DPI pin mode swap
- config mipi_tx current/impedance
lima:
- devfreq + cooling device support
- task handling improvements
- runtime PM support
pl111:
- vexpress init improvements
- fix module auto-load
rcar-du:
- DT bindings conversion to YAML
- Planes zpos sanity check and fix
- MAINTAINERS entry for LVDS panel driver
mcde:
- fix return value
mgag200:
- use managed config init
stm:
- read endpoints from DT
vboxvideo:
- use PCI managed functions
- drop WC mtrr
vkms:
- enable cursor by default
rockchip:
- afbc support
virtio:
- various cleanups
qxl:
- fix cursor notify port
hisilicon:
- 128-byte stride alignment fix
sun4i:
- improved format handling"
* tag 'drm-next-2020-06-02' of git://anongit.freedesktop.org/drm/drm: (1401 commits)
drm/amd/display: Fix potential integer wraparound resulting in a hang
drm/amd/display: drop cursor position check in atomic test
drm/amdgpu: fix device attribute node create failed with multi gpu
drm/nouveau: use correct conflicting framebuffer API
drm/vblank: Fix -Wformat compile warnings on some arches
drm/amdgpu: Sync with VM root BO when switching VM to CPU update mode
drm/amd/display: Handle GPU reset for DC block
drm/amdgpu: add apu flags (v2)
drm/amd/powerpay: Disable gfxoff when setting manual mode on picasso and raven
drm/amdgpu: fix pm sysfs node handling (v2)
drm/amdgpu: move gpu_info parsing after common early init
drm/amdgpu: move discovery gfx config fetching
drm/nouveau/dispnv50: fix runtime pm imbalance on error
drm/nouveau: fix runtime pm imbalance on error
drm/nouveau: fix runtime pm imbalance on error
drm/nouveau/debugfs: fix runtime pm imbalance on error
drm/nouveau/nouveau/hmm: fix migrate zero page to GPU
drm/nouveau/nouveau/hmm: fix nouveau_dmem_chunk allocations
drm/nouveau/kms/nv50-: Share DP SST mode_valid() handling with MST
drm/nouveau/kms/nv50-: Move 8BPC limit for MST into nv50_mstc_get_modes()
...
|
|
Merge updates from Andrew Morton:
"A few little subsystems and a start of a lot of MM patches.
Subsystems affected by this patch series: squashfs, ocfs2, parisc,
vfs. With mm subsystems: slab-generic, slub, debug, pagecache, gup,
swap, memcg, pagemap, memory-failure, vmalloc, kasan"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits)
kasan: move kasan_report() into report.c
mm/mm_init.c: report kasan-tag information stored in page->flags
ubsan: entirely disable alignment checks under UBSAN_TRAP
kasan: fix clang compilation warning due to stack protector
x86/mm: remove vmalloc faulting
mm: remove vmalloc_sync_(un)mappings()
x86/mm/32: implement arch_sync_kernel_mappings()
x86/mm/64: implement arch_sync_kernel_mappings()
mm/ioremap: track which page-table levels were modified
mm/vmalloc: track which page-table levels were modified
mm: add functions to track page directory modifications
s390: use __vmalloc_node in stack_alloc
powerpc: use __vmalloc_node in alloc_vm_stack
arm64: use __vmalloc_node in arch_alloc_vmap_stack
mm: remove vmalloc_user_node_flags
mm: switch the test_vmalloc module to use __vmalloc_node
mm: remove __vmalloc_node_flags_caller
mm: remove both instances of __vmalloc_node_flags
mm: remove the prot argument to __vmalloc_node
mm: remove the pgprot argument to __vmalloc
...
|
|
This is always PAGE_KERNEL - for long term mappings with other properties
vmap should be used.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/20200414131348.444715-19-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Doing a "get_user_pages()" on a copy-on-write page for reading can be
ambiguous: the page can be COW'ed at any time afterwards, and the
direction of a COW event isn't defined.
Yes, whoever writes to it will generally do the COW, but if the thread
that did the get_user_pages() unmapped the page before the write (and
that could happen due to memory pressure in addition to any outright
action), the writer could also just take over the old page instead.
End result: the get_user_pages() call might result in a page pointer
that is no longer associated with the original VM, and is associated
with - and controlled by - another VM having taken it over instead.
So when doing a get_user_pages() on a COW mapping, the only really safe
thing to do would be to break the COW when getting the page, even when
only getting it for reading.
At the same time, some users simply don't even care.
For example, the perf code wants to look up the page not because it
cares about the page, but because the code simply wants to look up the
physical address of the access for informational purposes, and doesn't
really care about races when a page might be unmapped and remapped
elsewhere.
This adds logic to force a COW event by setting FOLL_WRITE on any
copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page
pointer as a result.
The current semantics end up being:
- __get_user_pages_fast(): no change. If you don't ask for a write,
you won't break COW. You'd better know what you're doing.
- get_user_pages_fast(): the fast-case "look it up in the page tables
without anything getting mmap_sem" now refuses to follow a read-only
page, since it might need COW breaking. Which happens in the slow
path - the fast path doesn't know if the memory might be COW or not.
- get_user_pages() (including the slow-path fallback for gup_fast()):
for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with
very similar semantics to FOLL_FORCE.
If it turns out that we want finer granularity (ie "only break COW when
it might actually matter" - things like the zero page are special and
don't need to be broken) we might need to push these semantics deeper
into the lookup fault path. So if people care enough, it's possible
that we might end up adding a new internal FOLL_BREAK_COW flag to go
with the internal FOLL_COW flag we already have for tracking "I had a
COW".
Alternatively, if it turns out that different callers might want to
explicitly control the forced COW break behavior, we might even want to
make such a flag visible to the users of get_user_pages() instead of
using the above default semantics.
But for now, this is mostly commentary on the issue (this commit message
being a lot bigger than the patch, and that patch in turn is almost all
comments), with that minimal "enable COW breaking early" logic using the
existing FOLL_WRITE behavior.
[ It might be worth noting that we've always had this ambiguity, and it
could arguably be seen as a user-space issue.
You only get private COW mappings that could break either way in
situations where user space is doing cooperative things (ie fork()
before an execve() etc), but it _is_ surprising and very subtle, and
fork() is supposed to give you independent address spaces.
So let's treat this as a kernel issue and make the semantics of
get_user_pages() easier to understand. Note that obviously a true
shared mapping will still get a page that can change under us, so this
does _not_ mean that get_user_pages() somehow returns any "stable"
page ]
Reported-by: Jann Horn <jannh@google.com>
Tested-by: Christoph Hellwig <hch@lst.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill Shutemov <kirill@shutemov.name>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull uaccess/readdir updates from Al Viro:
"Finishing the conversion of readdir.c to unsafe_... API.
This includes the uaccess_{read,write}_begin series by Christophe
Leroy"
* 'uaccess.readdir' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
readdir.c: get rid of the last __put_user(), drop now-useless access_ok()
readdir.c: get compat_filldir() more or less in sync with filldir()
switch readdir(2) to unsafe_copy_dirent_name()
drm/i915/gem: Replace user_access_begin by user_write_access_begin
uaccess: Selectively open read or write user access
uaccess: Add user_read_access_begin/end and user_write_access_begin/end
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Name the object classes and their offspring for easier lockdep
debugging.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200529183204.16850-2-chris@chris-wilson.co.uk
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If we declare that an object type is shrinkable (any that we can reclaim
to recover system pages), make sure we taint the object mutex so that
lockdep expects us to use it within fs_reclaim. lockdep will then
complain the first time we try to allocate while holding the plain
mutex, as doing so invites potential recursion.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200529183204.16850-1-chris@chris-wilson.co.uk
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