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Currently, enabling CONFIG_STACKDEPOT means its stack_table will be
allocated from memblock, even if stack depot ends up not actually used.
The default size of stack_table is 4MB on 32-bit, 8MB on 64-bit.
This is fine for use-cases such as KASAN which is also a config option
and has overhead on its own. But it's an issue for functionality that
has to be actually enabled on boot (page_owner) or depends on hardware
(GPU drivers) and thus the memory might be wasted. This was raised as
an issue [1] when attempting to add stackdepot support for SLUB's debug
object tracking functionality. It's common to build kernels with
CONFIG_SLUB_DEBUG and enable slub_debug on boot only when needed, or
create only specific kmem caches with debugging for testing purposes.
It would thus be more efficient if stackdepot's table was allocated only
when actually going to be used. This patch thus makes the allocation
(and whole stack_depot_init() call) optional:
- Add a CONFIG_STACKDEPOT_ALWAYS_INIT flag to keep using the current
well-defined point of allocation as part of mem_init(). Make
CONFIG_KASAN select this flag.
- Other users have to call stack_depot_init() as part of their own init
when it's determined that stack depot will actually be used. This may
depend on both config and runtime conditions. Convert current users
which are page_owner and several in the DRM subsystem. Same will be
done for SLUB later.
- Because the init might now be called after the boot-time memblock
allocation has given all memory to the buddy allocator, change
stack_depot_init() to allocate stack_table with kvmalloc() when
memblock is no longer available. Also handle allocation failure by
disabling stackdepot (could have theoretically happened even with
memblock allocation previously), and don't unnecessarily align the
memblock allocation to its own size anymore.
[1] https://lore.kernel.org/all/CAMuHMdW=eoVzM1Re5FVoEN87nKfiLmM2+Ah7eNu2KXEhCvbZyA@mail.gmail.com/
Link: https://lkml.kernel.org/r/20211013073005.11351-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Marco Elver <elver@google.com> # stackdepot
Cc: Marco Elver <elver@google.com>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
From: Colin Ian King <colin.king@canonical.com>
Subject: lib/stackdepot: fix spelling mistake and grammar in pr_err message
There is a spelling mistake of the work allocation so fix this and
re-phrase the message to make it easier to read.
Link: https://lkml.kernel.org/r/20211015104159.11282-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
From: Vlastimil Babka <vbabka@suse.cz>
Subject: lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() - fixup
On FLATMEM, we call page_ext_init_flatmem_late() just before
kmem_cache_init() which means stack_depot_init() (called by page owner
init) will not recognize properly it should use kvmalloc() and not
memblock_alloc(). memblock_alloc() will also not issue a warning and
return a block memory that can be invalid and cause kernel page fault when
saving stacks, as reported by the kernel test robot [1].
Fix this by moving page_ext_init_flatmem_late() below kmem_cache_init() so
that slab_is_available() is true during stack_depot_init(). SPARSEMEM
doesn't have this issue, as it doesn't do page_ext_init_flatmem_late(),
but a different page_ext_init() even later in the boot process.
Thanks to Mike Rapoport for pointing out the FLATMEM init ordering issue.
While at it, also actually resolve a checkpatch warning in stack_depot_init()
from DRM CI, which was supposed to be in the original patch already.
[1] https://lore.kernel.org/all/20211014085450.GC18719@xsang-OptiPlex-9020/
Link: https://lkml.kernel.org/r/6abd9213-19a9-6d58-cedc-2414386d2d81@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: kernel test robot <oliver.sang@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
From: Vlastimil Babka <vbabka@suse.cz>
Subject: lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() - fixup3
Due to cd06ab2fd4 ("drm/locking: add backtrace for locking contended
locks without backoff") landing recently to -next adding a new stack depot
user in drivers/gpu/drm/drm_modeset_lock.c we need to add an appropriate
call to stack_depot_init() there as well.
Link: https://lkml.kernel.org/r/2a692365-cfa1-64f2-34e0-8aa5674dce5e@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Marco Elver <elver@google.com>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
From: Vlastimil Babka <vbabka@suse.cz>
Subject: lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() - fixup4
Due to 4e66934eaa ("lib: add reference counting tracking
infrastructure") landing recently to net-next adding a new stack depot
user in lib/ref_tracker.c we need to add an appropriate call to
stack_depot_init() there as well.
Link: https://lkml.kernel.org/r/45c1b738-1a2f-5b5f-2f6d-86fab206d01c@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Cc: Jiri Slab <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Skipping just one branch of the tree is not the most
effective approach.
Instead use a macro to define the traversal functions and
sort out both branch sides.
This improves the performance of the unit tests by
a factor of more than 4.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nirmoy Das <nirmoy.das@amd.com>
Link: https://patchwork.freedesktop.org/patch/370298/
When the current entry is rejected as candidate for the search
it does not mean that we can abort the subtree search.
It is perfectly possible that only the alignment, but not the
size is the reason for the rejection.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nirmoy Das <nirmoy.das@amd.com>
Link: https://patchwork.freedesktop.org/patch/369394/
Userspace can severely fragment rb_hole_addr rbtree by manipulating
alignment while allocating buffers. Fragmented rb_hole_addr rbtree
would result in large delays while allocating buffer object for a
userspace application. It takes long time to find suitable hole
because if we fail to find a suitable hole in the first attempt
then we look for neighbouring nodes using rb_prev()/rb_next().
Traversing rbtree using rb_prev()/rb_next() can take really long
time if the tree is fragmented.
This patch improves searches in fragmented rb_hole_addr rbtree by
modifying it to an augmented rbtree which will store an extra field
in drm_mm_node, subtree_max_hole. Each drm_mm_node now stores maximum
hole size for its subtree in drm_mm_node->subtree_max_hole. Using
drm_mm_node->subtree_max_hole, it is possible to eliminate a complete
subtree if that subtree is unable to serve a request hence reducing
number of rb_prev()/rb_next() used.
With this patch applied, 1 million bo allocs on amdgpu took ~8 sec,
compared to 50k bo allocs which took 28 sec without it.
partial test code:
int test_fragmentation(void)
{
int i = 0;
uint32_t minor_version;
uint32_t major_version;
struct amdgpu_bo_alloc_request request = {};
amdgpu_bo_handle vram_handle[MAX_ALLOC] = {};
amdgpu_device_handle device_handle;
request.alloc_size = 4096;
request.phys_alignment = 8192;
request.preferred_heap = AMDGPU_GEM_DOMAIN_VRAM;
int fd = open("/dev/dri/card0", O_RDWR | O_CLOEXEC);
amdgpu_device_initialize(fd, &major_version, &minor_version,
&device_handle);
for (i = 0; i < MAX_ALLOC; i++) {
amdgpu_bo_alloc(device_handle, &request, &vram_handle[i]);
}
for (i = 0; i < MAX_ALLOC; i++)
amdgpu_bo_free(vram_handle[i]);
return 0;
}
v2:
Use RB_DECLARE_CALLBACKS_MAX to maintain subtree_max_hole
v3:
insert_hole_addr() should be static a function
fix return value of next_hole_high_addr()/next_hole_low_addr()
Reported-by: kbuild test robot <lkp@intel.com>
v4:
Fix commit message.
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/364341/
Signed-off-by: Christian König <christian.koenig@amd.com>
We try hard to select a suitable hole in the drm_mm first time. But if
that is unsuccessful, we then have to look at neighbouring nodes, and
this requires traversing the rbtree. Walking the rbtree can be slow
(much slower than a linear list for deep trees), and if the drm_mm has
been purposefully fragmented our search can be trapped for a long, long
time. For non-preemptible kernels, we need to break up long CPU bound
sections by manually checking for cond_resched(); similarly we should
also bail out if we have been told to terminate. (In an ideal world, we
would break for any signal, but we need to trade off having to perform
the search again after ERESTARTSYS, which again may form a trap of
making no forward progress.)
Reported-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200207151720.2812125-1-chris@chris-wilson.co.uk
A few callers need to serialise the destruction of their drm_mm_node and
ensure it is removed from the drm_mm before freeing. However, to be
completely sure that any access from another thread is complete before
we free the struct, we require the RELEASE semantics of
clear_bit_unlock().
This allows the conditional locking such as
Thread A Thread B
mutex_lock(mm_lock); if (drm_mm_node_allocated(node)) {
drm_mm_node_remove(node); mutex_lock(mm_lock);
mutex_unlock(mm_lock); if (drm_mm_node_allocated(node))
drm_mm_node_remove(node);
mutex_unlock(mm_lock);
}
kfree(node);
to serialise correctly without any lingering accesses from A to the
freed node. Allocation / insertion of the node is assumed never to race
with removal or eviction scanning.
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/20191003210100.22250-5-chris@chris-wilson.co.uk
Searching for an available hole by address is slow, as there no
guarantee that a hole will be available and so we must walk over all
nodes in the rbtree before we determine the search was futile. In many
cases, the caller doesn't strictly care for the highest available hole
and was just opportunistically laying out the address space in a
preferred order. In such cases, the caller can accept any address and
would rather do so then do a slow walk.
To be able to mix search strategies, the caller wants to tell the drm_mm
how long to spend on the search. Without a good guide for what should be
the best split, start with a request to try once at most. That is return
the top-most (or lowest) hole if it fulfils the alignment and size
requirements.
v2: Documentation, by why of example (selftests) and kerneldoc.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180521082131.13744-2-chris@chris-wilson.co.uk
As we keep an rbtree of available holes sorted by their size, we can
very easily determine if there is any hole large enough that might
satisfy the allocation request. This helps when dealing with a highly
fragmented address space and a request for a search by address.
To cache the largest size, we convert into the cached rbtree variant
which tracks the leftmost node for us. However, currently we sorted into
ascending size order so the leftmost node is the smallest, and so to
make it the largest hole we need to invert our sorting.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180521082131.13744-1-chris@chris-wilson.co.uk
Fixes for 4.16. I contains fixes for deadlock on runtime suspend on few
drivers, a memory leak on non-blocking commits, a crash on color-eviction.
The is also meson and edid fixes, plus a fix for a doc warning.
* tag 'drm-misc-fixes-2018-02-21' of git://anongit.freedesktop.org/drm/drm-misc:
drm/tve200: fix kernel-doc documentation comment include
drm/meson: fix vsync buffer update
drm: Handle unexpected holes in color-eviction
drm/edid: Add 6 bpc quirk for CPT panel in Asus UX303LA
drm/amdgpu: Fix deadlock on runtime suspend
drm/radeon: Fix deadlock on runtime suspend
drm/nouveau: Fix deadlock on runtime suspend
drm: Allow determining if current task is output poll worker
workqueue: Allow retrieval of current task's work struct
drm/atomic: Fix memleak on ERESTARTSYS during non-blocking commits
Insulate users from changes to the internal hole tracking within
struct drm_mm_node by using an accessor for hole_follows.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
[danvet: resolve conflicts in i915_vma.c]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Using mm->color_adjust makes the eviction scanner much tricker since we
don't know the actual neighbours of the target hole until after it is
created (after scanning is complete). To work out whether we need to
evict the neighbours because they impact upon the hole, we have to then
check the hole afterwards - requiring an extra step in the user of the
eviction scanner when they apply color_adjust.
v2: Massage kerneldoc.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-34-chris@chris-wilson.co.uk
The scan state occupies a large proportion of the struct drm_mm and is
rarely used and only contains temporary state. That makes it suitable to
moving to its struct and onto the stack of the callers.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
[danvet: Fix up etnaviv to compile, was missing a BUG_ON.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
