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As we want to re-use intel_vgpu_shadow_page in buidling scrach page table
and we don't want to put scrach page table page into hash table, a new
param is introduced to give the caller a choice to decide if a shadow page
should be put into hash table.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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As there is already an I915_GTT_PAGE_SIZE marco in i915, let GVT-g use it
as well. Also this patch re-names some GTT marcos with additional prefix.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Since many emulation logic needs to convert the offset of ring registers
into ring id, we export it for other caller which might need it.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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As the data structure of "intel_vgpu_guest_page" will become much heavier
in future, it's better to factor out the guest memory page track mechnisim
as early as possible.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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1) Use standard i915 GEM object sequence to access the shadow batch buffer.
2) Manage i915 vma life cycle to solve one FIXME.
v2:
- Refine code structure.
- Refine the usage of GEM APIs.
- Add the missing lock/unlock in release_shadow_batch_buffer.
Test on my SKL NuC.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Returns the error code if something is wrong and the size of batch buffer
is passed through the pointer.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Replace the plain bit usage with BIT() to make klockwork happy.
Cc: Deng Hongyi <hongyi.deng@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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We need debugfs entry to expose some debug information of gvt and vGPUs.
The first tool will be added is mmio-diff, which help to find the
difference values of host and vGPU mmio. It's useful for platform
enabling.
This patch just add a basic debugfs infrastructure, each vGPU has its own
sub-folder. Two simple attributes are created as a template.
.
├── num_tracked_mmio
├── vgpu1
| └── active
└── vgpu2
└── active
Signed-off-by: Changbin Du <changbin.du@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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all the vGPU type related code in kvmgt will be moved into
gvt.c/gvt.h files while the common vGPU type related interfaces
will be called.
v2:
- intel_gvt_{init,cleanup}_vgpu_type_groups are initialized in
gvt part. (Wang, Zhi)
Signed-off-by: fred gao <fred.gao@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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In this patch, all the vGPU type related code will be merged into
same gvt file and the common interface will be exposed to both
XenGT and KvmGT.
v2:
- remove the useless mdev_* gvt_ops.
add get_gvt_attr ops for MPT module.
intel_gvt_{init,cleanup}_vgpu_type_groups are initialized in
gvt part. (Wang, Zhi)
- set gvt_vgpu_type_groups[i] to NULL. (Zhang,Xiong)
Signed-off-by: fred gao <fred.gao@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Move clean_workloads() into scheduler.c since it's not specific to
execlist.
v2:
- Remove clean_workloads in intel_vgpu_select_submission_ops. (Zhenyu)
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Introduce an generic API to reset vGPU virtual submission interface.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Introduce vGPU submission ops to support easy switching submission mode
of one vGPU between different OSes.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Now the function has been moved into scheduler.c. The extra declaration
is not necessary.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Move common vGPU workload creation functions into scheduler.c since
they are not specific to execlist emulation.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Move common workload preparation into prepare_workload() in scheduler.c,
as they are not specific to execlist emulation.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Factor out prepare_workload() for the following re-factor.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Factor out vGPU workload creation/destroy functions since they are not
specific to execlist emulation.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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It's better enable/disable and classify gvt debug info dynamically.
This patch change it to dyndbg so can be dynamically enable/disable
each item. All gvt log can be enabled by,
$ echo 'file *gvt* +p' > /sys/kernel/debug/dynamic_debug/control
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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An earlier fix changed the return type from find_bb_size however the
integer return is being assigned to a unsigned int so the -ve error
check will never be detected. Make bb_size an int to fix this.
Detected by CoverityScan CID#1456886 ("Unsigned compared against 0")
Fixes: 1e3197d6ad73 ("drm/i915/gvt: Refine error handling for perform_bb_shadow")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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When a scan error occurs in submit_context, this patch is to
decrease the mm ref count and free the workload struct before
the workload is abandoned.
v2:
- submit_context related code should be combined together. (Zhenyu)
v3:
- free all the unsubmitted workloads. (Zhenyu)
v4:
- refine the clean path. (Zhenyu)
v5:
- polish the title. (Zhenyu)
Signed-off-by: fred gao <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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When a scan error occurs in dispatch_workload, this patch is to
check the healthy state and free all the queued workloads before
the failsafe mode is entered.
Signed-off-by: fred gao <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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Generally, there are 3 types of errors during command scan: a) some
commands might be unknown with EBADRQC; b) some cmd access invalid
address with EFAULT; c) some unexpected force nonpriv cmd with EPERM.
later the healthy state can be judged through the return error.
v2:
- remove some internal i915 errors rating. (Zhenyu)
v3:
- the healthy state is judged through the internal defined return
error. (Zhenyu)
- force non priv cmd error can be ignored. (Kevin)
v4:
- reuse standard defined errno instead of recreate, e.g EBADRQC for
unknown cmd, EFAULT for invalid address, EPERM for nonpriv. (Zhenyu)
v5:
- remove some irrelevant code for the patch.
- fix typo of vgpu_is_vm_unhealthy. (Zhenyu)
v6:
- move the healthy check and failsafe code into another patch. (Zhenyu)
v7:
- polish title and commit message. (Zhenyu)
Signed-off-by: fred gao <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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Theoretically, the largest bulk of commands in the ring buffer of an
engine might be the first submission, which usually contains a lot
of commands to initialize the HW. After removing the initial allocation
of the ring scan buffer and let krealloc() do everything we need, we
still have a big chance to get the buffer of suitable size in the first
submission.
Tested on my SKL NUC.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Move ring scan buffers into intel_vgpu_submission since they belongs to
a part of vGPU submission stuffs.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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"reserved" means reserve something from somewhere. Actually they are
buffers used by command scanner. Rename it to ring_scan_buffer.
v2:
- Remove the usage of an extra variable. (Zhenyu)
Fixes: 0a53bc07f044 ("drm/i915/gvt: Separate cmd scan from request allocation")
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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The pointer points to the original memory can never take the return value
of krealloc().
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Move tlb_handle_pending into intel_vgpu_submssion since it belongs to a
part of vGPU submission stuffs
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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Introduce intel_vgpu_submission to hold all members related to submission
in struct intel_vgpu before.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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clean}_submission()
Move vGPU workload cache initialization/de-initialization into
intel_vgpu_{setup, clean}_submission() since they are not specific to
execlist stuffs.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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To move workload related functions into scheduler.c, an expected way is
to collect all the init/clean functions related to vGPU workload
submission into fewer functions.
Rename intel_vgpu_{init, clean}_gvt_context() for above usage in future.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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The context descriptors in elsp_dwords are stored in a reversed order and
the definition of context descriptor is also reversed. The revesred stuff
is hard to be used and might cause misunderstanding. Make them in the right
oder for following code re-factoring.
Tested on my SKL NUC.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
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opregion emulated with a copy from host which leads to some display
bugs such as guest resolution adjustment failure due to host opregion
fail to claim port D support. with a fake opregion table provided
to fully emulate opregion to meet guest port requirement.
v1 - initial patch
v2 - reforamt opregion arrary with 0x02x output
v3 - opregion array removed with opregion generation on host initizaiton
v4 - rebased v3 patch from stable branch to staging branch which also has
different struct child_device_config and addressed v3 review comments.
Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
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Merge updates from Andrew Morton:
- a few misc bits
- ocfs2 updates
- almost all of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (131 commits)
memory hotplug: fix comments when adding section
mm: make alloc_node_mem_map a void call if we don't have CONFIG_FLAT_NODE_MEM_MAP
mm: simplify nodemask printing
mm,oom_reaper: remove pointless kthread_run() error check
mm/page_ext.c: check if page_ext is not prepared
writeback: remove unused function parameter
mm: do not rely on preempt_count in print_vma_addr
mm, sparse: do not swamp log with huge vmemmap allocation failures
mm/hmm: remove redundant variable align_end
mm/list_lru.c: mark expected switch fall-through
mm/shmem.c: mark expected switch fall-through
mm/page_alloc.c: broken deferred calculation
mm: don't warn about allocations which stall for too long
fs: fuse: account fuse_inode slab memory as reclaimable
mm, page_alloc: fix potential false positive in __zone_watermark_ok
mm: mlock: remove lru_add_drain_all()
mm, sysctl: make NUMA stats configurable
shmem: convert shmem_init_inodecache() to void
Unify migrate_pages and move_pages access checks
mm, pagevec: rename pagevec drained field
...
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into drm-next
Various fixes for DC for 4.15.
* 'drm-next-4.15-dc' of git://people.freedesktop.org/~agd5f/linux:
drm/amd/display: fix MST link training fail division by 0
drm/amd/display: Fix formatting for null pointer dereference fix
drm/amd/display: Remove dangling planes on dc commit state
drm/amd/display: add flip_immediate to commit update for stream
drm/amd/display: Miss register MST encoder cbs
drm/amd/display: Fix warnings on S3 resume
drm/amd/display: use num_timing_generator instead of pipe_count
drm/amd/display: use configurable FBC option in dm
drm/amd/display: fix AZ clock not enabled before program AZ endpoint
amdgpu/dm: Don't use DRM_ERROR in amdgpu_dm_atomic_check
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Here, pfn_to_node should be page_to_nid.
Link: http://lkml.kernel.org/r/1510735205-22540-1-git-send-email-fan.du@intel.com
Signed-off-by: Fan Du <fan.du@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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CONFIG_FLAT_NODE_MEM_MAP
free_area_init_node() calls alloc_node_mem_map(), but this function does
nothing unless we have CONFIG_FLAT_NODE_MEM_MAP.
As a cleanup, we can move the "#ifdef CONFIG_FLAT_NODE_MEM_MAP" within
alloc_node_mem_map() out of the function, and define a
alloc_node_mem_map() { } when CONFIG_FLAT_NODE_MEM_MAP is not present.
This also moves the printk that lays within the "#ifdef
CONFIG_FLAT_NODE_MEM_MAP" block from free_area_init_node() to
alloc_node_mem_map(), getting rid of the "#ifdef
CONFIG_FLAT_NODE_MEM_MAP" in free_area_init_node().
[akpm@linux-foundation.org: clean up the printk while we're there]
Link: http://lkml.kernel.org/r/20171114111935.GA11758@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@techadventures.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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alloc_warn() and dump_header() have to explicitly handle NULL nodemask
which forces both paths to use pr_cont. We can do better. printk
already handles NULL pointers properly so all we need is to teach
nodemask_pr_args to handle NULL nodemask carefully. This allows
simplification of both alloc_warn() and dump_header() and gets rid of
pr_cont altogether.
This patch has been motivated by patch from Joe Perches
http://lkml.kernel.org/r/b31236dfe3fc924054fd7842bde678e71d193638.1509991345.git.joe@perches.com
[akpm@linux-foundation.org: fix tile warning, per Arnd]
Link: http://lkml.kernel.org/r/20171109100531.3cn2hcqnuj7mjaju@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Joe Perches <joe@perches.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since oom_init() is called before userspace processes start, memory
allocation failure for creating the OOM reaper kernel thread will let
the OOM killer call panic() rather than wake up the OOM reaper.
Link: http://lkml.kernel.org/r/1510137800-4602-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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online_page_ext() and page_ext_init() allocate page_ext for each
section, but they do not allocate if the first PFN is !pfn_present(pfn)
or !pfn_valid(pfn). Then section->page_ext remains as NULL.
lookup_page_ext checks NULL only if CONFIG_DEBUG_VM is enabled. For a
valid PFN, __set_page_owner will try to get page_ext through
lookup_page_ext. Without CONFIG_DEBUG_VM lookup_page_ext will misuse
NULL pointer as value 0. This incurrs invalid address access.
This is the panic example when PFN 0x100000 is not valid but PFN
0x13FC00 is being used for page_ext. section->page_ext is NULL,
get_entry returned invalid page_ext address as 0x1DFA000 for a PFN
0x13FC00.
To avoid this panic, CONFIG_DEBUG_VM should be removed so that page_ext
will be checked at all times.
Unable to handle kernel paging request at virtual address 01dfa014
------------[ cut here ]------------
Kernel BUG at ffffff80082371e0 [verbose debug info unavailable]
Internal error: Oops: 96000045 [#1] PREEMPT SMP
Modules linked in:
PC is at __set_page_owner+0x48/0x78
LR is at __set_page_owner+0x44/0x78
__set_page_owner+0x48/0x78
get_page_from_freelist+0x880/0x8e8
__alloc_pages_nodemask+0x14c/0xc48
__do_page_cache_readahead+0xdc/0x264
filemap_fault+0x2ac/0x550
ext4_filemap_fault+0x3c/0x58
__do_fault+0x80/0x120
handle_mm_fault+0x704/0xbb0
do_page_fault+0x2e8/0x394
do_mem_abort+0x88/0x124
Pre-4.7 kernels also need commit f86e4271978b ("mm: check the return
value of lookup_page_ext for all call sites").
Link: http://lkml.kernel.org/r/20171107094131.14621-1-jaewon31.kim@samsung.com
Fixes: eefa864b701d ("mm/page_ext: resurrect struct page extending code for debugging")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: <stable@vger.kernel.org> [depends on f86e427197, see above]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The parameter `struct bdi_writeback *wb` is not been used in the
function body. Remove it.
Link: http://lkml.kernel.org/r/1509685485-15278-1-git-send-email-wanglong19@meituan.com
Signed-off-by: Wang Long <wanglong19@meituan.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The preempt count check on print_vma_addr has been added by commit
e8bff74afbdb ("x86: fix "BUG: sleeping function called from invalid
context" in print_vma_addr()") and it relied on the elevated preempt
count from preempt_conditional_sti because preempt_count check doesn't
work on non preemptive kernels by default.
The code has evolved though and commit d99e1bd175f4 ("x86/entry/traps:
Refactor preemption and interrupt flag handling") has replaced
preempt_conditional_sti by an explicit preempt_disable which is noop on
!PREEMPT so the check in print_vma_addr is broken.
Fix the issue by using trylock on mmap_sem rather than chacking the
preempt count. The allocation we are relying on has to be GFP_NOWAIT as
well. There is a chance that we won't dump the vma state if the lock is
contended or the memory short but this is acceptable outcome and much
less fragile than the not working preemption check or tricks around it.
Link: http://lkml.kernel.org/r/20171106134031.g6dbelg55mrbyc6i@dhcp22.suse.cz
Fixes: d99e1bd175f4 ("x86/entry/traps: Refactor preemption and interrupt flag handling")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Yang Shi <yang.s@alibaba-inc.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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While doing memory hotplug tests under heavy memory pressure we have
noticed too many page allocation failures when allocating vmemmap memmap
backed by huge page
kworker/u3072:1: page allocation failure: order:9, mode:0x24084c0(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO)
[...]
Call Trace:
dump_trace+0x59/0x310
show_stack_log_lvl+0xea/0x170
show_stack+0x21/0x40
dump_stack+0x5c/0x7c
warn_alloc_failed+0xe2/0x150
__alloc_pages_nodemask+0x3ed/0xb20
alloc_pages_current+0x7f/0x100
vmemmap_alloc_block+0x79/0xb6
__vmemmap_alloc_block_buf+0x136/0x145
vmemmap_populate+0xd2/0x2b9
sparse_mem_map_populate+0x23/0x30
sparse_add_one_section+0x68/0x18e
__add_pages+0x10a/0x1d0
arch_add_memory+0x4a/0xc0
add_memory_resource+0x89/0x160
add_memory+0x6d/0xd0
acpi_memory_device_add+0x181/0x251
acpi_bus_attach+0xfd/0x19b
acpi_bus_scan+0x59/0x69
acpi_device_hotplug+0xd2/0x41f
acpi_hotplug_work_fn+0x1a/0x23
process_one_work+0x14e/0x410
worker_thread+0x116/0x490
kthread+0xbd/0xe0
ret_from_fork+0x3f/0x70
and we do see many of those because essentially every allocation fails
for each memory section. This is an excessive way to tell the user that
there is nothing to really worry about because we do have a fallback
mechanism to use base pages. The only downside might be a performance
degradation due to TLB pressure.
This patch changes vmemmap_alloc_block() to use __GFP_NOWARN and warn
explicitly once on the first allocation failure. This will reduce the
noise in the kernel log considerably, while we still have an indication
that a performance might be impacted.
[mhocko@kernel.org: forgot to git add the follow up fix]
Link: http://lkml.kernel.org/r/20171107090635.c27thtse2lchjgvb@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20171106092228.31098-1-mhocko@kernel.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Joe Perches <joe@perches.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Variable align_end is assigned a value but it is never read, so the
variable is redundant and can be removed. Cleans up the clang warning:
Value stored to 'align_end' is never read
Link: http://lkml.kernel.org/r/20171017143837.23207-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In preparation for enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Link: http://lkml.kernel.org/r/20171020190754.GA24332@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Link: http://lkml.kernel.org/r/20171020191058.GA24427@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In reset_deferred_meminit() we determine number of pages that must not
be deferred. We initialize pages for at least 2G of memory, but also
pages for reserved memory in this node.
The reserved memory is determined in this function:
memblock_reserved_memory_within(), which operates over physical
addresses, and returns size in bytes. However, reset_deferred_meminit()
assumes that that this function operates with pfns, and returns page
count.
The result is that in the best case machine boots slower than expected
due to initializing more pages than needed in single thread, and in the
worst case panics because fewer than needed pages are initialized early.
Link: http://lkml.kernel.org/r/20171021011707.15191-1-pasha.tatashin@oracle.com
Fixes: 864b9a393dcb ("mm: consider memblock reservations for deferred memory initialization sizing")
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Commit 63f53dea0c98 ("mm: warn about allocations which stall for too
long") was a great step for reducing possibility of silent hang up
problem caused by memory allocation stalls. But this commit reverts it,
for it is possible to trigger OOM lockup and/or soft lockups when many
threads concurrently called warn_alloc() (in order to warn about memory
allocation stalls) due to current implementation of printk(), and it is
difficult to obtain useful information due to limitation of synchronous
warning approach.
Current printk() implementation flushes all pending logs using the
context of a thread which called console_unlock(). printk() should be
able to flush all pending logs eventually unless somebody continues
appending to printk() buffer.
Since warn_alloc() started appending to printk() buffer while waiting
for oom_kill_process() to make forward progress when oom_kill_process()
is processing pending logs, it became possible for warn_alloc() to force
oom_kill_process() loop inside printk(). As a result, warn_alloc()
significantly increased possibility of preventing oom_kill_process()
from making forward progress.
---------- Pseudo code start ----------
Before warn_alloc() was introduced:
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
}
goto retry;
After warn_alloc() was introduced:
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
} else if (waited_for_10seconds()) {
atomic_inc(&printk_pending_logs);
}
goto retry;
---------- Pseudo code end ----------
Although waited_for_10seconds() becomes true once per 10 seconds,
unbounded number of threads can call waited_for_10seconds() at the same
time. Also, since threads doing waited_for_10seconds() keep doing
almost busy loop, the thread doing print_one_log() can use little CPU
resource. Therefore, this situation can be simplified like
---------- Pseudo code start ----------
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
} else {
atomic_inc(&printk_pending_logs);
}
goto retry;
---------- Pseudo code end ----------
when printk() is called faster than print_one_log() can process a log.
One of possible mitigation would be to introduce a new lock in order to
make sure that no other series of printk() (either oom_kill_process() or
warn_alloc()) can append to printk() buffer when one series of printk()
(either oom_kill_process() or warn_alloc()) is already in progress.
Such serialization will also help obtaining kernel messages in readable
form.
---------- Pseudo code start ----------
retry:
if (mutex_trylock(&oom_lock)) {
mutex_lock(&oom_printk_lock);
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_printk_lock);
mutex_unlock(&oom_lock)
} else {
if (mutex_trylock(&oom_printk_lock)) {
atomic_inc(&printk_pending_logs);
mutex_unlock(&oom_printk_lock);
}
}
goto retry;
---------- Pseudo code end ----------
But this commit does not go that direction, for we don't want to
introduce a new lock dependency, and we unlikely be able to obtain
useful information even if we serialized oom_kill_process() and
warn_alloc().
Synchronous approach is prone to unexpected results (e.g. too late [1],
too frequent [2], overlooked [3]). As far as I know, warn_alloc() never
helped with providing information other than "something is going wrong".
I want to consider asynchronous approach which can obtain information
during stalls with possibly relevant threads (e.g. the owner of
oom_lock and kswapd-like threads) and serve as a trigger for actions
(e.g. turn on/off tracepoints, ask libvirt daemon to take a memory dump
of stalling KVM guest for diagnostic purpose).
This commit temporarily loses ability to report e.g. OOM lockup due to
unable to invoke the OOM killer due to !__GFP_FS allocation request.
But asynchronous approach will be able to detect such situation and emit
warning. Thus, let's remove warn_alloc().
[1] https://bugzilla.kernel.org/show_bug.cgi?id=192981
[2] http://lkml.kernel.org/r/CAM_iQpWuPVGc2ky8M-9yukECtS+zKjiDasNymX7rMcBjBFyM_A@mail.gmail.com
[3] commit db73ee0d46379922 ("mm, vmscan: do not loop on too_many_isolated for ever"))
Link: http://lkml.kernel.org/r/1509017339-4802-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Reported-by: yuwang.yuwang <yuwang.yuwang@alibaba-inc.com>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Fuse inodes are currently included in the unreclaimable slab counts -
SUnreclaim in /proc/meminfo, slab_unreclaimable in /proc/vmstat and the
per-cgroup memory.stat. But they are reclaimable just like other
filesystems' inodes, and /proc/sys/vm/drop_caches frees them easily.
Mark the slab cache reclaimable.
Link: http://lkml.kernel.org/r/20171102202727.12539-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Since commit 97a16fc82a7c ("mm, page_alloc: only enforce watermarks for
order-0 allocations"), __zone_watermark_ok() check for high-order
allocations will shortcut per-migratetype free list checks for
ALLOC_HARDER allocations, and return true as long as there's free page
of any migratetype. The intention is that ALLOC_HARDER can allocate
from MIGRATE_HIGHATOMIC free lists, while normal allocations can't.
However, as a side effect, the watermark check will then also return
true when there are pages only on the MIGRATE_ISOLATE list, or (prior to
CMA conversion to ZONE_MOVABLE) on the MIGRATE_CMA list. Since the
allocation cannot actually obtain isolated pages, and might not be able
to obtain CMA pages, this can result in a false positive.
The condition should be rare and perhaps the outcome is not a fatal one.
Still, it's better if the watermark check is correct. There also
shouldn't be a performance tradeoff here.
Link: http://lkml.kernel.org/r/20171102125001.23708-1-vbabka@suse.cz
Fixes: 97a16fc82a7c ("mm, page_alloc: only enforce watermarks for order-0 allocations")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
