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* mm: memcontrol: account kernel stack per nodeShakeel Butt2020-08-079-61/+55
| | | | | | | | | | | | | | | | | Currently the kernel stack is being accounted per-zone. There is no need to do that. In addition due to being per-zone, memcg has to keep a separate MEMCG_KERNEL_STACK_KB. Make the stat per-node and deprecate MEMCG_KERNEL_STACK_KB as memcg_stat_item is an extension of node_stat_item. In addition localize the kernel stack stats updates to account_kernel_stack(). Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Link: http://lkml.kernel.org/r/20200630161539.1759185-1-shakeelb@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tools/cgroup: add memcg_slabinfo.py toolRoman Gushchin2020-08-071-0/+226
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a drgn-based tool to display slab information for a given memcg. Can replace cgroup v1 memory.kmem.slabinfo interface on cgroup v2, but in a more flexiable way. Currently supports only SLUB configuration, but SLAB can be trivially added later. Output example: $ sudo ./tools/cgroup/memcg_slabinfo.py /sys/fs/cgroup/user.slice/user-111017.slice/user\@111017.service shmem_inode_cache 92 92 704 46 8 : tunables 0 0 0 : slabdata 2 2 0 eventpoll_pwq 56 56 72 56 1 : tunables 0 0 0 : slabdata 1 1 0 eventpoll_epi 32 32 128 32 1 : tunables 0 0 0 : slabdata 1 1 0 kmalloc-8 0 0 8 512 1 : tunables 0 0 0 : slabdata 0 0 0 kmalloc-96 0 0 96 42 1 : tunables 0 0 0 : slabdata 0 0 0 kmalloc-2048 0 0 2048 16 8 : tunables 0 0 0 : slabdata 0 0 0 kmalloc-64 128 128 64 64 1 : tunables 0 0 0 : slabdata 2 2 0 mm_struct 160 160 1024 32 8 : tunables 0 0 0 : slabdata 5 5 0 signal_cache 96 96 1024 32 8 : tunables 0 0 0 : slabdata 3 3 0 sighand_cache 45 45 2112 15 8 : tunables 0 0 0 : slabdata 3 3 0 files_cache 138 138 704 46 8 : tunables 0 0 0 : slabdata 3 3 0 task_delay_info 153 153 80 51 1 : tunables 0 0 0 : slabdata 3 3 0 task_struct 27 27 3520 9 8 : tunables 0 0 0 : slabdata 3 3 0 radix_tree_node 56 56 584 28 4 : tunables 0 0 0 : slabdata 2 2 0 btrfs_inode 140 140 1136 28 8 : tunables 0 0 0 : slabdata 5 5 0 kmalloc-1024 64 64 1024 32 8 : tunables 0 0 0 : slabdata 2 2 0 kmalloc-192 84 84 192 42 2 : tunables 0 0 0 : slabdata 2 2 0 inode_cache 54 54 600 27 4 : tunables 0 0 0 : slabdata 2 2 0 kmalloc-128 0 0 128 32 1 : tunables 0 0 0 : slabdata 0 0 0 kmalloc-512 32 32 512 32 4 : tunables 0 0 0 : slabdata 1 1 0 skbuff_head_cache 32 32 256 32 2 : tunables 0 0 0 : slabdata 1 1 0 sock_inode_cache 46 46 704 46 8 : tunables 0 0 0 : slabdata 1 1 0 cred_jar 378 378 192 42 2 : tunables 0 0 0 : slabdata 9 9 0 proc_inode_cache 96 96 672 24 4 : tunables 0 0 0 : slabdata 4 4 0 dentry 336 336 192 42 2 : tunables 0 0 0 : slabdata 8 8 0 filp 697 864 256 32 2 : tunables 0 0 0 : slabdata 27 27 0 anon_vma 644 644 88 46 1 : tunables 0 0 0 : slabdata 14 14 0 pid 1408 1408 64 64 1 : tunables 0 0 0 : slabdata 22 22 0 vm_area_struct 1200 1200 200 40 2 : tunables 0 0 0 : slabdata 30 30 0 Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200623174037.3951353-20-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kselftests: cgroup: add kernel memory accounting testsRoman Gushchin2020-08-073-0/+385
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add some tests to cover the kernel memory accounting functionality. These are covering some issues (and changes) we had recently. 1) A test which allocates a lot of negative dentries, checks memcg slab statistics, creates memory pressure by setting memory.max to some low value and checks that some number of slabs was reclaimed. 2) A test which covers side effects of memcg destruction: it creates and destroys a large number of sub-cgroups, each containing a multi-threaded workload which allocates and releases some kernel memory. Then it checks that the charge ans memory.stats do add up on the parent level. 3) A test which reads /proc/kpagecgroup and implicitly checks that it doesn't crash the system. 4) A test which spawns a large number of threads and checks that the kernel stacks accounting works as expected. 5) A test which checks that living charged slab objects are not preventing the memory cgroup from being released after being deleted by a user. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200623174037.3951353-19-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: use a single set of kmem_caches for all allocationsRoman Gushchin2020-08-078-590/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Naresh Kamboju <naresh.kamboju@linaro.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo()Roman Gushchin2020-08-071-3/+0
| | | | | | | | | | | | | | | | | memcg_accumulate_slabinfo() is never called with a non-root kmem_cache as a first argument, so the is_root_cache(s) check is redundant and can be removed without any functional change. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-17-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: deprecate slab_root_cachesRoman Gushchin2020-08-074-48/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently there are two lists of kmem_caches: 1) slab_caches, which contains all kmem_caches, 2) slab_root_caches, which contains only root kmem_caches. And there is some preprocessor magic to have a single list if CONFIG_MEMCG_KMEM isn't enabled. It was required earlier because the number of non-root kmem_caches was proportional to the number of memory cgroups and could reach really big values. Now, when it cannot exceed the number of root kmem_caches, there is really no reason to maintain two lists. We never iterate over the slab_root_caches list on any hot paths, so it's perfectly fine to iterate over slab_caches and filter out non-root kmem_caches. It allows to remove a lot of config-dependent code and two pointers from the kmem_cache structure. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-16-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: remove memcg_kmem_get_cache()Roman Gushchin2020-08-074-29/+11
| | | | | | | | | | | | | | | | | | | The memcg_kmem_get_cache() function became really trivial, so let's just inline it into the single call point: memcg_slab_pre_alloc_hook(). It will make the code less bulky and can also help the compiler to generate a better code. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-15-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: simplify memcg cache creationRoman Gushchin2020-08-074-58/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because the number of non-root kmem_caches doesn't depend on the number of memory cgroups anymore and is generally not very big, there is no more need for a dedicated workqueue. Also, as there is no more need to pass any arguments to the memcg_create_kmem_cache() except the root kmem_cache, it's possible to just embed the work structure into the kmem_cache and avoid the dynamic allocation of the work structure. This will also simplify the synchronization: for each root kmem_cache there is only one work. So there will be no more concurrent attempts to create a non-root kmem_cache for a root kmem_cache: the second and all following attempts to queue the work will fail. On the kmem_cache destruction path there is no more need to call the expensive flush_workqueue() and wait for all pending works to be finished. Instead, cancel_work_sync() can be used to cancel/wait for only one work. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-14-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: use a single set of kmem_caches for all accounted allocationsRoman Gushchin2020-08-077-698/+134
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is fairly big but mostly red patch, which makes all accounted slab allocations use a single set of kmem_caches instead of creating a separate set for each memory cgroup. Because the number of non-root kmem_caches is now capped by the number of root kmem_caches, there is no need to shrink or destroy them prematurely. They can be perfectly destroyed together with their root counterparts. This allows to dramatically simplify the management of non-root kmem_caches and delete a ton of code. This patch performs the following changes: 1) introduces memcg_params.memcg_cache pointer to represent the kmem_cache which will be used for all non-root allocations 2) reuses the existing memcg kmem_cache creation mechanism to create memcg kmem_cache on the first allocation attempt 3) memcg kmem_caches are named <kmemcache_name>-memcg, e.g. dentry-memcg 4) simplifies memcg_kmem_get_cache() to just return memcg kmem_cache or schedule it's creation and return the root cache 5) removes almost all non-root kmem_cache management code (separate refcounter, reparenting, shrinking, etc) 6) makes slab debugfs to display root_mem_cgroup css id and never show :dead and :deact flags in the memcg_slabinfo attribute. Following patches in the series will simplify the kmem_cache creation. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-13-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.hRoman Gushchin2020-08-072-12/+12
| | | | | | | | | | | | | | | | | | | To make the memcg_kmem_bypass() function available outside of the memcontrol.c, let's move it to memcontrol.h. The function is small and nicely fits into static inline sort of functions. It will be used from the slab code. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-12-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: deprecate memory.kmem.slabinfoRoman Gushchin2020-08-072-30/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Deprecate memory.kmem.slabinfo. An empty file will be presented if corresponding config options are enabled. The interface is implementation dependent, isn't present in cgroup v2, and is generally useful only for core mm debugging purposes. In other words, it doesn't provide any value for the absolute majority of users. A drgn-based replacement can be found in tools/cgroup/memcg_slabinfo.py. It does support cgroup v1 and v2, mimics memory.kmem.slabinfo output and also allows to get any additional information without a need to recompile the kernel. If a drgn-based solution is too slow for a task, a bpf-based tracing tool can be used, which can easily keep track of all slab allocations belonging to a memory cgroup. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-11-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: charge individual slab objects instead of pagesRoman Gushchin2020-08-071-96/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Switch to per-object accounting of non-root slab objects. Charging is performed using obj_cgroup API in the pre_alloc hook. Obj_cgroup is charged with the size of the object and the size of metadata: as now it's the size of an obj_cgroup pointer. If the amount of memory has been charged successfully, the actual allocation code is executed. Otherwise, -ENOMEM is returned. In the post_alloc hook if the actual allocation succeeded, corresponding vmstats are bumped and the obj_cgroup pointer is saved. Otherwise, the charge is canceled. On the free path obj_cgroup pointer is obtained and used to uncharge the size of the releasing object. Memcg and lruvec counters are now representing only memory used by active slab objects and do not include the free space. The free space is shared and doesn't belong to any specific cgroup. Global per-node slab vmstats are still modified from (un)charge_slab_page() functions. The idea is to keep all slab pages accounted as slab pages on system level. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-10-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: save obj_cgroup for non-root slab objectsRoman Gushchin2020-08-075-21/+88
| | | | | | | | | | | | | | | | | | | | | | | | | Store the obj_cgroup pointer in the corresponding place of page->obj_cgroups for each allocated non-root slab object. Make sure that each allocated object holds a reference to obj_cgroup. Objcg pointer is obtained from the memcg->objcg dereferencing in memcg_kmem_get_cache() and passed from pre_alloc_hook to post_alloc_hook. Then in case of successful allocation(s) it's getting stored in the page->obj_cgroups vector. The objcg obtaining part look a bit bulky now, but it will be simplified by next commits in the series. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-9-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: allocate obj_cgroups for non-root slab pagesRoman Gushchin2020-08-075-4/+81
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allocate and release memory to store obj_cgroup pointers for each non-root slab page. Reuse page->mem_cgroup pointer to store a pointer to the allocated space. This commit temporarily increases the memory footprint of the kernel memory accounting. To store obj_cgroup pointers we'll need a place for an objcg_pointer for each allocated object. However, the following patches in the series will enable sharing of slab pages between memory cgroups, which will dramatically increase the total slab utilization. And the final memory footprint will be significantly smaller than before. To distinguish between obj_cgroups and memcg pointers in case when it's not obvious which one is used (as in page_cgroup_ino()), let's always set the lowest bit in the obj_cgroup case. The original obj_cgroups pointer is marked to be ignored by kmemleak, which otherwise would report a memory leak for each allocated vector. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-8-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg/slab: obj_cgroup APIRoman Gushchin2020-08-072-1/+338
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Obj_cgroup API provides an ability to account sub-page sized kernel objects, which potentially outlive the original memory cgroup. The top-level API consists of the following functions: bool obj_cgroup_tryget(struct obj_cgroup *objcg); void obj_cgroup_get(struct obj_cgroup *objcg); void obj_cgroup_put(struct obj_cgroup *objcg); int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size); void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size); struct mem_cgroup *obj_cgroup_memcg(struct obj_cgroup *objcg); struct obj_cgroup *get_obj_cgroup_from_current(void); Object cgroup is basically a pointer to a memory cgroup with a per-cpu reference counter. It substitutes a memory cgroup in places where it's necessary to charge a custom amount of bytes instead of pages. All charged memory rounded down to pages is charged to the corresponding memory cgroup using __memcg_kmem_charge(). It implements reparenting: on memcg offlining it's getting reattached to the parent memory cgroup. Each online memory cgroup has an associated active object cgroup to handle new allocations and the list of all attached object cgroups. On offlining of a cgroup this list is reparented and for each object cgroup in the list the memcg pointer is swapped to the parent memory cgroup. It prevents long-living objects from pinning the original memory cgroup in the memory. The implementation is based on byte-sized per-cpu stocks. A sub-page sized leftover is stored in an atomic field, which is a part of obj_cgroup object. So on cgroup offlining the leftover is automatically reparented. memcg->objcg is rcu protected. objcg->memcg is a raw pointer, which is always pointing at a memory cgroup, but can be atomically swapped to the parent memory cgroup. So a user must ensure the lifetime of the cgroup, e.g. grab rcu_read_lock or css_set_lock. Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200623174037.3951353-7-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcontrol: decouple reference counting from page accountingJohannes Weiner2020-08-072-20/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The reference counting of a memcg is currently coupled directly to how many 4k pages are charged to it. This doesn't work well with Roman's new slab controller, which maintains pools of objects and doesn't want to keep an extra balance sheet for the pages backing those objects. This unusual refcounting design (reference counts usually track pointers to an object) is only for historical reasons: memcg used to not take any css references and simply stalled offlining until all charges had been reparented and the page counters had dropped to zero. When we got rid of the reparenting requirement, the simple mechanical translation was to take a reference for every charge. More historical context can be found in commit e8ea14cc6ead ("mm: memcontrol: take a css reference for each charged page"), commit 64f219938941 ("mm: memcontrol: remove obsolete kmemcg pinning tricks") and commit b2052564e66d ("mm: memcontrol: continue cache reclaim from offlined groups"). The new slab controller exposes the limitations in this scheme, so let's switch it to a more idiomatic reference counting model based on actual kernel pointers to the memcg: - The per-cpu stock holds a reference to the memcg its caching - User pages hold a reference for their page->mem_cgroup. Transparent huge pages will no longer acquire tail references in advance, we'll get them if needed during the split. - Kernel pages hold a reference for their page->mem_cgroup - Pages allocated in the root cgroup will acquire and release css references for simplicity. css_get() and css_put() optimize that. - The current memcg_charge_slab() already hacked around the per-charge references; this change gets rid of that as well. - tcp accounting will handle reference in mem_cgroup_sk_{alloc,free} Roman: 1) Rebased on top of the current mm tree: added css_get() in mem_cgroup_charge(), dropped mem_cgroup_try_charge() part 2) I've reformatted commit references in the commit log to make checkpatch.pl happy. [hughd@google.com: remove css_put_many() from __mem_cgroup_clear_mc()] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2007302011450.2347@eggly.anvils Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200623174037.3951353-6-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: slub: implement SLUB version of obj_to_index()Roman Gushchin2020-08-072-10/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit implements SLUB version of the obj_to_index() function, which will be required to calculate the offset of obj_cgroup in the obj_cgroups vector to store/obtain the objcg ownership data. To make it faster, let's repeat the SLAB's trick introduced by commit 6a2d7a955d8d ("SLAB: use a multiply instead of a divide in obj_to_index()") and avoid an expensive division. Vlastimil Babka noticed, that SLUB does have already a similar function called slab_index(), which is defined only if SLUB_DEBUG is enabled. The function does a similar math, but with a division, and it also takes a page address instead of a page pointer. Let's remove slab_index() and replace it with the new helper __obj_to_index(), which takes a page address. obj_to_index() will be a simple wrapper taking a page pointer and passing page_address(page) into __obj_to_index(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-5-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg: convert vmstat slab counters to bytesRoman Gushchin2020-08-0713-42/+53
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to prepare for per-object slab memory accounting, convert NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE vmstat items to bytes. To make it obvious, rename them to NR_SLAB_RECLAIMABLE_B and NR_SLAB_UNRECLAIMABLE_B (similar to NR_KERNEL_STACK_KB). Internally global and per-node counters are stored in pages, however memcg and lruvec counters are stored in bytes. This scheme may look weird, but only for now. As soon as slab pages will be shared between multiple cgroups, global and node counters will reflect the total number of slab pages. However memcg and lruvec counters will be used for per-memcg slab memory tracking, which will take separate kernel objects in the account. Keeping global and node counters in pages helps to avoid additional overhead. The size of slab memory shouldn't exceed 4Gb on 32-bit machines, so it will fit into atomic_long_t we use for vmstats. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg: prepare for byte-sized vmstat itemsRoman Gushchin2020-08-075-10/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To implement per-object slab memory accounting, we need to convert slab vmstat counters to bytes. Actually, out of 4 levels of counters: global, per-node, per-memcg and per-lruvec only two last levels will require byte-sized counters. It's because global and per-node counters will be counting the number of slab pages, and per-memcg and per-lruvec will be counting the amount of memory taken by charged slab objects. Converting all vmstat counters to bytes or even all slab counters to bytes would introduce an additional overhead. So instead let's store global and per-node counters in pages, and memcg and lruvec counters in bytes. To make the API clean all access helpers (both on the read and write sides) are dealing with bytes. To avoid back-and-forth conversions a new flavor of read-side helpers is introduced, which always returns values in pages: node_page_state_pages() and global_node_page_state_pages(). Actually new helpers are just reading raw values. Old helpers are simple wrappers, which will complain on an attempt to read byte value, because at the moment no one actually needs bytes. Thanks to Johannes Weiner for the idea of having the byte-sized API on top of the page-sized internal storage. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcg: factor out memcg- and lruvec-level changes out of ↵Roman Gushchin2020-08-072-19/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __mod_lruvec_state() Patch series "The new cgroup slab memory controller", v7. The patchset moves the accounting from the page level to the object level. It allows to share slab pages between memory cgroups. This leads to a significant win in the slab utilization (up to 45%) and the corresponding drop in the total kernel memory footprint. The reduced number of unmovable slab pages should also have a positive effect on the memory fragmentation. The patchset makes the slab accounting code simpler: there is no more need in the complicated dynamic creation and destruction of per-cgroup slab caches, all memory cgroups use a global set of shared slab caches. The lifetime of slab caches is not more connected to the lifetime of memory cgroups. The more precise accounting does require more CPU, however in practice the difference seems to be negligible. We've been using the new slab controller in Facebook production for several months with different workloads and haven't seen any noticeable regressions. What we've seen were memory savings in order of 1 GB per host (it varied heavily depending on the actual workload, size of RAM, number of CPUs, memory pressure, etc). The third version of the patchset added yet another step towards the simplification of the code: sharing of slab caches between accounted and non-accounted allocations. It comes with significant upsides (most noticeable, a complete elimination of dynamic slab caches creation) but not without some regression risks, so this change sits on top of the patchset and is not completely merged in. So in the unlikely event of a noticeable performance regression it can be reverted separately. The slab memory accounting works in exactly the same way for SLAB and SLUB. With both allocators the new controller shows significant memory savings, with SLUB the difference is bigger. On my 16-core desktop machine running Fedora 32 the size of the slab memory measured after the start of the system was lower by 58% and 38% with SLUB and SLAB correspondingly. As an estimation of a potential CPU overhead, below are results of slab_bulk_test01 test, kindly provided by Jesper D. Brouer. He also helped with the evaluation of results. The test can be found here: https://github.com/netoptimizer/prototype-kernel/ The smallest number in each row should be picked for a comparison. SLUB-patched - bulk-API - SLUB-patched : bulk_quick_reuse objects=1 : 187 - 90 - 224 cycles(tsc) - SLUB-patched : bulk_quick_reuse objects=2 : 110 - 53 - 133 cycles(tsc) - SLUB-patched : bulk_quick_reuse objects=3 : 88 - 95 - 42 cycles(tsc) - SLUB-patched : bulk_quick_reuse objects=4 : 91 - 85 - 36 cycles(tsc) - SLUB-patched : bulk_quick_reuse objects=8 : 32 - 66 - 32 cycles(tsc) SLUB-original - bulk-API - SLUB-original: bulk_quick_reuse objects=1 : 87 - 87 - 142 cycles(tsc) - SLUB-original: bulk_quick_reuse objects=2 : 52 - 53 - 53 cycles(tsc) - SLUB-original: bulk_quick_reuse objects=3 : 42 - 42 - 91 cycles(tsc) - SLUB-original: bulk_quick_reuse objects=4 : 91 - 37 - 37 cycles(tsc) - SLUB-original: bulk_quick_reuse objects=8 : 31 - 79 - 76 cycles(tsc) SLAB-patched - bulk-API - SLAB-patched : bulk_quick_reuse objects=1 : 67 - 67 - 140 cycles(tsc) - SLAB-patched : bulk_quick_reuse objects=2 : 55 - 46 - 46 cycles(tsc) - SLAB-patched : bulk_quick_reuse objects=3 : 93 - 94 - 39 cycles(tsc) - SLAB-patched : bulk_quick_reuse objects=4 : 35 - 88 - 85 cycles(tsc) - SLAB-patched : bulk_quick_reuse objects=8 : 30 - 30 - 30 cycles(tsc) SLAB-original- bulk-API - SLAB-original: bulk_quick_reuse objects=1 : 143 - 136 - 67 cycles(tsc) - SLAB-original: bulk_quick_reuse objects=2 : 45 - 46 - 46 cycles(tsc) - SLAB-original: bulk_quick_reuse objects=3 : 38 - 39 - 39 cycles(tsc) - SLAB-original: bulk_quick_reuse objects=4 : 35 - 87 - 87 cycles(tsc) - SLAB-original: bulk_quick_reuse objects=8 : 29 - 66 - 30 cycles(tsc) This patch (of 19): To convert memcg and lruvec slab counters to bytes there must be a way to change these counters without touching node counters. Factor out __mod_memcg_lruvec_state() out of __mod_lruvec_state(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-1-guro@fb.com Link: http://lkml.kernel.org/r/20200623174037.3951353-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kmem: make memcg_kmem_enabled() irreversibleRoman Gushchin2020-08-071-6/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Historically the kernel memory accounting was an opt-in feature, which could be enabled for individual cgroups. But now it's not true, and it's on by default both on cgroup v1 and cgroup v2. And as long as a user has at least one non-root memory cgroup, the kernel memory accounting is on. So in most setups it's either always on (if memory cgroups are in use and kmem accounting is not disabled), either always off (otherwise). memcg_kmem_enabled() is used in many places to guard the kernel memory accounting code. If memcg_kmem_enabled() can reverse from returning true to returning false (as now), we can't rely on it on release paths and have to check if it was on before. If we'll make memcg_kmem_enabled() irreversible (always returning true after returning it for the first time), it'll make the general logic more simple and robust. It also will allow to guard some checks which otherwise would stay unguarded. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200702180926.1330769-1-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tmpfs: support 64-bit inums per-sbChris Down2020-08-074-2/+103
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The default is still set to inode32 for backwards compatibility, but system administrators can opt in to the new 64-bit inode numbers by either: 1. Passing inode64 on the command line when mounting, or 2. Configuring the kernel with CONFIG_TMPFS_INODE64=y The inode64 and inode32 names are used based on existing precedent from XFS. [hughd@google.com: Kconfig fixes] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008011928010.13320@eggly.anvils Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/8b23758d0c66b5e2263e08baf9c4b6a7565cbd8f.1594661218.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tmpfs: per-superblock i_ino supportChris Down2020-08-073-5/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "tmpfs: inode: Reduce risk of inum overflow", v7. In Facebook production we are seeing heavy i_ino wraparounds on tmpfs. On affected tiers, in excess of 10% of hosts show multiple files with different content and the same inode number, with some servers even having as many as 150 duplicated inode numbers with differing file content. This causes actual, tangible problems in production. For example, we have complaints from those working on remote caches that their application is reporting cache corruptions because it uses (device, inodenum) to establish the identity of a particular cache object, but because it's not unique any more, the application refuses to continue and reports cache corruption. Even worse, sometimes applications may not even detect the corruption but may continue anyway, causing phantom and hard to debug behaviour. In general, userspace applications expect that (device, inodenum) should be enough to be uniquely point to one inode, which seems fair enough. One might also need to check the generation, but in this case: 1. That's not currently exposed to userspace (ioctl(...FS_IOC_GETVERSION...) returns ENOTTY on tmpfs); 2. Even with generation, there shouldn't be two live inodes with the same inode number on one device. In order to mitigate this, we take a two-pronged approach: 1. Moving inum generation from being global to per-sb for tmpfs. This itself allows some reduction in i_ino churn. This works on both 64- and 32- bit machines. 2. Adding inode{64,32} for tmpfs. This fix is supported on machines with 64-bit ino_t only: we allow users to mount tmpfs with a new inode64 option that uses the full width of ino_t, or CONFIG_TMPFS_INODE64. You can see how this compares to previous related patches which didn't implement this per-superblock: - https://patchwork.kernel.org/patch/11254001/ - https://patchwork.kernel.org/patch/11023915/ This patch (of 2): get_next_ino has a number of problems: - It uses and returns a uint, which is susceptible to become overflowed if a lot of volatile inodes that use get_next_ino are created. - It's global, with no specificity per-sb or even per-filesystem. This means it's not that difficult to cause inode number wraparounds on a single device, which can result in having multiple distinct inodes with the same inode number. This patch adds a per-superblock counter that mitigates the second case. This design also allows us to later have a specific i_ino size per-device, for example, allowing users to choose whether to use 32- or 64-bit inodes for each tmpfs mount. This is implemented in the next commit. For internal shmem mounts which may be less tolerant to spinlock delays, we implement a percpu batching scheme which only takes the stat_lock at each batch boundary. Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Hugh Dickins <hughd@google.com> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/cover.1594661218.git.chris@chrisdown.name Link: http://lkml.kernel.org/r/1986b9d63b986f08ec07a4aa4b2275e718e47d8a.1594661218.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_io.c: use blk_io_schedule() for avoiding task hung in sync ioXianting Tian2020-08-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | swap_readpage() does the sync io for one page, the io is not big, normally, the io can be finished quickly, but it may take long time or wait forever in case of io failure or discard. This patch uses blk_io_schedule() instead of io_schedule() to avoid task hung and crash (when set /proc/sys/kernel/hung_task_panic) when the above exception occurs. This is similar to the hung task avoidance in submit_bio_wait(), blk_execute_rq() and __blkdev_direct_IO(). Signed-off-by: Xianting Tian <xianting_tian@126.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ming Lei <ming.lei@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Hannes Reinecke <hare@suse.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/1596461807-21087-1-git-send-email-xianting_tian@126.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: swap: fix kerneldoc of swap_vma_readahead()Krzysztof Kozlowski2020-08-071-1/+1
| | | | | | | | | | | | | Fix W=1 compile warnings (invalid kerneldoc): mm/swap_state.c:742: warning: Function parameter or member 'fentry' not described in 'swap_vma_readahead' mm/swap_state.c:742: warning: Excess function parameter 'entry' description in 'swap_vma_readahead' Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200728171109.28687-2-krzk@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap_slots.c: remove redundant check for swap_slot_cache_initializedZhen Lei2020-08-071-3/+2
| | | | | | | | | | | | | | | | | | | | | | | Because enable_swap_slots_cache can only become true in enable_swap_slots_cache(), and depends on swap_slot_cache_initialized is true before. That means, when enable_swap_slots_cache is true, swap_slot_cache_initialized is true also. So the condition: "swap_slot_cache_enabled && swap_slot_cache_initialized" can be reduced to "swap_slot_cache_enabled" And in mathematics: "!swap_slot_cache_enabled || !swap_slot_cache_initialized" is equal to "!(swap_slot_cache_enabled && swap_slot_cache_initialized)" So no functional change. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Link: http://lkml.kernel.org/r/20200430061143.450-4-thunder.leizhen@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap_slots.c: simplify enable_swap_slots_cache()Zhen Lei2020-08-071-12/+10
| | | | | | | | | | | | | | | | Whether swap_slot_cache_initialized is true or false, __reenable_swap_slots_cache() is always called. To make this meaning clear, leave only one call to __reenable_swap_slots_cache(). This also make it clearer what extra needs be done when swap_slot_cache_initialized is false. No functional change. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Link: http://lkml.kernel.org/r/20200430061143.450-3-thunder.leizhen@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap_slots.c: simplify alloc_swap_slot_cache()Zhen Lei2020-08-071-9/+9
| | | | | | | | | | | | | | | | | | | | | Patch series "clean up some functions in mm/swap_slots.c". When I studied the code of mm/swap_slots.c, I found some places can be improved. This patch (of 3): Both "slots" and "slots_ret" are only need to be freed when cache already allocated. Make them closer, seems more clear. No functional change. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Link: http://lkml.kernel.org/r/20200430061143.450-1-thunder.leizhen@huawei.com Link: http://lkml.kernel.org/r/20200430061143.450-2-thunder.leizhen@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup.c: fix the comment of return value for populate_vma_page_range()Tang Yizhou2020-08-071-1/+2
| | | | | | | | | | | | The return value of populate_vma_page_range() is consistent with __get_user_pages(), and so is the function comment of return value. Signed-off-by: Tang Yizhou <tangyizhou@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Link: http://lkml.kernel.org/r/20200720034303.29920-1-tangyizhou@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: filemap: add missing FGP_ flags in kerneldoc comment for pagecache_get_pageYang Shi2020-08-071-0/+3
| | | | | | | | | | | | | | FGP_{WRITE|NOFS|NOWAIT} were missed in pagecache_get_page's kerneldoc comment. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Gang Deng <gavin.dg@linux.alibaba.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/1593031747-4249-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: filemap: clear idle flag for writesYang Shi2020-08-071-0/+6
| | | | | | | | | | | | | | | | | | | | | | | Since commit bbddabe2e436aa ("mm: filemap: only do access activations on reads"), mark_page_accessed() is called for reads only. But the idle flag is cleared by mark_page_accessed() so the idle flag won't get cleared if the page is write accessed only. Basically idle page tracking is used to estimate workingset size of workload, noticeable size of workingset might be missed if the idle flag is not maintained correctly. It seems good enough to just clear idle flag for write operations. Fixes: bbddabe2e436 ("mm: filemap: only do access activations on reads") Reported-by: Gang Deng <gavin.dg@linux.alibaba.com> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/1593020612-13051-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, dump_page: do not crash with bad compound_mapcount()John Hubbard2020-08-072-5/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a compound page is being split while dump_page() is being run on that page, we can end up calling compound_mapcount() on a page that is no longer compound. This leads to a crash (already seen at least once in the field), due to the VM_BUG_ON_PAGE() assertion inside compound_mapcount(). (The above is from Matthew Wilcox's analysis of Qian Cai's bug report.) A similar problem is possible, via compound_pincount() instead of compound_mapcount(). In order to avoid this kind of crash, make dump_page() slightly more robust, by providing a pair of simpler routines that don't contain assertions: head_mapcount() and head_pincount(). For debug tools, we don't want to go *too* far in this direction, but this is a simple small fix, and the crash has already been seen, so it's a good trade-off. Reported-by: Qian Cai <cai@lca.pw> Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200804214807.169256-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: print hashed address of struct pageMatthew Wilcox (Oracle)2020-08-071-4/+4
| | | | | | | | | | | | | | | | | The actual address of the struct page isn't particularly helpful, while the hashed address helps match with other messages elsewhere. Add the PFN that the page refers to in order to help diagnose problems where the page is improperly aligned for the purpose. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200709202117.7216-7-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: print the inode number in dump_pageMatthew Wilcox (Oracle)2020-08-071-3/+3
| | | | | | | | | | | | | | | The inode number helps correlate this page with debug messages elsewhere in the kernel. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200709202117.7216-6-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: switch dump_page to get_kernel_nofaultMatthew Wilcox (Oracle)2020-08-071-20/+16
| | | | | | | | | | | | | | | This is simpler to use than copy_from_kernel_nofault(). Also make some of the related error messages less verbose. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200709202117.7216-5-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: print head flags in dump_pageMatthew Wilcox (Oracle)2020-08-071-1/+1
| | | | | | | | | | | | | | | | | | Tail page flags contain very little useful information. Print the head page's flags instead. While the flags will contain "head" for tail pages, this should not be too confusing as the previous line starts with the word "head:" and so the flags should be interpreted as belonging to the head page. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200709202117.7216-4-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: dump compound page information on a second lineMatthew Wilcox (Oracle)2020-08-071-18/+12
| | | | | | | | | | | | | | | | | Simplify both the implementation and the output by splitting all the compound page information onto a second line. Reported-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: William Kucharski <william.kucharski@oracle.com> Link: http://lkml.kernel.org/r/20200709202117.7216-3-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug: handle page->mapping better in dump_pageMatthew Wilcox (Oracle)2020-08-071-2/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "Improvements for dump_page()", v2. Here's a sample dump of a pagecache tail page with all of the patches applied: page:000000006d1c49ca refcount:6 mapcount:0 mapping:00000000136b8d90 index:0x109 pfn:0x6c645 head:000000008bd38076 order:2 compound_mapcount:0 compound_pincount:0 aops:xfs_address_space_operations ino:800042 dentry name:"fd" flags: 0x4000000000012014(uptodate|lru|private|head) raw: 4000000000000000 ffffd46ac1b19101 ffffffff00000202 dead000000000004 raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 head: 4000000000012014 ffffd46ac1b1bbc8 ffffd46ac1b1bc08 ffff91976f659560 head: 0000000000000108 ffff919773220680 00000006ffffffff 0000000000000000 page dumped because: testing This patch (of 6): If we can't call page_mapping() to get the page mapping, handle the anon/ksm/movable bits correctly. [akpm@linux-foundation.org: augmented code comment from John] Link: http://lkml.kernel.org/r/15cff11a-6762-8a6a-3f0e-dd227280cd6f@nvidia.com Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Link: http://lkml.kernel.org/r/20200709202117.7216-1-willy@infradead.org Link: http://lkml.kernel.org/r/20200709202117.7216-2-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Documentation/mm: add descriptions for arch page table helpersAnshuman Khandual2020-08-072-0/+264
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a specific description file for all arch page table helpers which is in sync with the semantics being tested via CONFIG_DEBUG_VM_PGTABLE. All future changes either to these descriptions here or the debug test should always remain in sync. [anshuman.khandual@arm.com: fold in Mike's patch for the rst document, fix typos in the rst document] Link: http://lkml.kernel.org/r/1594610587-4172-5-git-send-email-anshuman.khandual@arm.com Suggested-by: Mike Rapoport <rppt@kernel.org> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Zi Yan <ziy@nvidia.com> Link: http://lkml.kernel.org/r/1593996516-7186-5-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug_vm_pgtable: add debug prints for individual testsAnshuman Khandual2020-08-071-1/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds debug print information that enlists all tests getting executed on a given platform. With dynamic debug enabled, the following information will be splashed during boot. For compactness purpose, dropped both time stamp and prefix (i.e debug_vm_pgtable) from this sample output. [debug_vm_pgtable ]: Validating architecture page table helpers [pte_basic_tests ]: Validating PTE basic [pmd_basic_tests ]: Validating PMD basic [p4d_basic_tests ]: Validating P4D basic [pgd_basic_tests ]: Validating PGD basic [pte_clear_tests ]: Validating PTE clear [pmd_clear_tests ]: Validating PMD clear [pte_advanced_tests ]: Validating PTE advanced [pmd_advanced_tests ]: Validating PMD advanced [hugetlb_advanced_tests]: Validating HugeTLB advanced [pmd_leaf_tests ]: Validating PMD leaf [pmd_huge_tests ]: Validating PMD huge [pte_savedwrite_tests ]: Validating PTE saved write [pmd_savedwrite_tests ]: Validating PMD saved write [pmd_populate_tests ]: Validating PMD populate [pte_special_tests ]: Validating PTE special [pte_protnone_tests ]: Validating PTE protnone [pmd_protnone_tests ]: Validating PMD protnone [pte_devmap_tests ]: Validating PTE devmap [pmd_devmap_tests ]: Validating PMD devmap [pte_swap_tests ]: Validating PTE swap [swap_migration_tests ]: Validating swap migration [hugetlb_basic_tests ]: Validating HugeTLB basic [pmd_thp_tests ]: Validating PMD based THP Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Vineet Gupta <vgupta@synopsys.com> [arc] Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Link: http://lkml.kernel.org/r/1593996516-7186-4-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug_vm_pgtable: add tests validating advanced arch page table helpersAnshuman Khandual2020-08-071-0/+312
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds new tests validating for these following arch advanced page table helpers. These tests create and test specific mapping types at various page table levels. 1. pxxp_set_wrprotect() 2. pxxp_get_and_clear() 3. pxxp_set_access_flags() 4. pxxp_get_and_clear_full() 5. pxxp_test_and_clear_young() 6. pxx_leaf() 7. pxx_set_huge() 8. pxx_(clear|mk)_savedwrite() 9. huge_pxxp_xxx() [anshuman.khandual@arm.com: drop RANDOM_ORVALUE from hugetlb_advanced_tests()] Link: http://lkml.kernel.org/r/1594610587-4172-3-git-send-email-anshuman.khandual@arm.com Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Vineet Gupta <vgupta@synopsys.com> [arc] Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Steven Price <steven.price@arm.com> Link: http://lkml.kernel.org/r/1593996516-7186-3-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/debug_vm_pgtable: add tests validating arch helpers for core MM featuresAnshuman Khandual2020-08-071-1/+301
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm/debug_vm_pgtable: Add some more tests", v5. This series adds some more arch page table helper validation tests which are related to core and advanced memory functions. This also creates a documentation, enlisting expected semantics for all page table helpers as suggested by Mike Rapoport previously (https://lkml.org/lkml/2020/1/30/40). There are many TRANSPARENT_HUGEPAGE and ARCH_HAS_TRANSPARENT_HUGEPAGE_PUD ifdefs scattered across the test. But consolidating all the fallback stubs is not very straight forward because ARCH_HAS_TRANSPARENT_HUGEPAGE_PUD is not explicitly dependent on ARCH_HAS_TRANSPARENT_HUGEPAGE. Tested on arm64, x86 platforms but only build tested on all other enabled platforms through ARCH_HAS_DEBUG_VM_PGTABLE i.e powerpc, arc, s390. The following failure on arm64 still exists which was mentioned previously. It will be fixed with the upcoming THP migration on arm64 enablement series. WARNING .... mm/debug_vm_pgtable.c:860 debug_vm_pgtable+0x940/0xa54 WARN_ON(!pmd_present(pmd_mkinvalid(pmd_mkhuge(pmd)))) This patch (of 4): This adds new tests validating arch page table helpers for these following core memory features. These tests create and test specific mapping types at various page table levels. 1. SPECIAL mapping 2. PROTNONE mapping 3. DEVMAP mapping 4. SOFTDIRTY mapping 5. SWAP mapping 6. MIGRATION mapping 7. HUGETLB mapping 8. THP mapping Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Vineet Gupta <vgupta@synopsys.com> [arc] Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mike Rapoport <rppt@kernel.org> Cc: Steven Price <steven.price@arm.com> Link: http://lkml.kernel.org/r/1594610587-4172-1-git-send-email-anshuman.khandual@arm.com Link: http://lkml.kernel.org/r/1593996516-7186-1-git-send-email-anshuman.khandual@arm.com Link: http://lkml.kernel.org/r/1593996516-7186-2-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, kcsan: instrument SLAB/SLUB free with "ASSERT_EXCLUSIVE_ACCESS"Marco Elver2020-08-072-0/+10
| | | | | | | | | | | | | | | | | | | | | | | Provide the necessary KCSAN checks to assist with debugging racy use-after-frees. While KASAN is more reliable at generally catching such use-after-frees (due to its use of a quarantine), it can be difficult to debug racy use-after-frees. If a reliable reproducer exists, KCSAN can assist in debugging such issues. Note: ASSERT_EXCLUSIVE_ACCESS is a convenience wrapper if the size is simply sizeof(var). Instead, here we just use __kcsan_check_access() explicitly to pass the correct size. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200623072653.114563-1-elver@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/slub.c: drop lockdep_assert_held() from put_map()Sebastian Andrzej Siewior2020-08-071-2/+0
| | | | | | | | | | | | | | | | | | | There is no point in using lockdep_assert_held() unlock that is about to be unlocked. It works only with lockdep and lockdep will complain if spin_unlock() is used on a lock that has not been locked. Remove superfluous lockdep_assert_held(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Christopher Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20200618201234.795692-2-bigeasy@linutronix.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slab/slub: improve error reporting and overhead of cache_from_obj()Vlastimil Babka2020-08-073-45/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cache_from_obj() was added by commit b9ce5ef49f00 ("sl[au]b: always get the cache from its page in kmem_cache_free()") to support kmemcg, where per-memcg cache can be different from the root one, so we can't use the kmem_cache pointer given to kmem_cache_free(). Prior to that commit, SLUB already had debugging check+warning that could be enabled to compare the given kmem_cache pointer to one referenced by the slab page where the object-to-be-freed resides. This check was moved to cache_from_obj(). Later the check was also enabled for SLAB_FREELIST_HARDENED configs by commit 598a0717a816 ("mm/slab: validate cache membership under freelist hardening"). These checks and warnings can be useful especially for the debugging, which can be improved. Commit 598a0717a816 changed the pr_err() with WARN_ON_ONCE() to WARN_ONCE() so only the first hit is now reported, others are silent. This patch changes it to WARN() so that all errors are reported. It's also useful to print SLUB allocation/free tracking info for the offending object, if tracking is enabled. Thus, export the SLUB print_tracking() function and provide an empty one for SLAB. For SLUB we can also benefit from the static key check in kmem_cache_debug_flags(), but we need to move this function to slab.h and declare the static key there. [1] https://lore.kernel.org/r/20200608230654.828134-18-guro@fb.com [vbabka@suse.cz: avoid bogus WARN()] Link: https://lore.kernel.org/r/20200623090213.GW5535@shao2-debian Link: http://lkml.kernel.org/r/b33e0fa7-cd28-4788-9e54-5927846329ef@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Roman Gushchin <guro@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Garrett <mjg59@google.com> Cc: Jann Horn <jannh@google.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Link: http://lkml.kernel.org/r/afeda7ac-748b-33d8-a905-56b708148ad5@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slab/slub: move and improve cache_from_obj()Vlastimil Babka2020-08-073-23/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The function cache_from_obj() was added by commit b9ce5ef49f00 ("sl[au]b: always get the cache from its page in kmem_cache_free()") to support kmemcg, where per-memcg cache can be different from the root one, so we can't use the kmem_cache pointer given to kmem_cache_free(). Prior to that commit, SLUB already had debugging check+warning that could be enabled to compare the given kmem_cache pointer to one referenced by the slab page where the object-to-be-freed resides. This check was moved to cache_from_obj(). Later the check was also enabled for SLAB_FREELIST_HARDENED configs by commit 598a0717a816 ("mm/slab: validate cache membership under freelist hardening"). These checks and warnings can be useful especially for the debugging, which can be improved. Commit 598a0717a816 changed the pr_err() with WARN_ON_ONCE() to WARN_ONCE() so only the first hit is now reported, others are silent. This patch changes it to WARN() so that all errors are reported. It's also useful to print SLUB allocation/free tracking info for the offending object, if tracking is enabled. We could export the SLUB print_tracking() function and provide an empty one for SLAB, or realize that both the debugging and hardening cases in cache_from_obj() are only supported by SLUB anyway. So this patch moves cache_from_obj() from slab.h to separate instances in slab.c and slub.c, where the SLAB version only does the kmemcg lookup and even could be completely removed once the kmemcg rework [1] is merged. The SLUB version can thus easily use the print_tracking() function. It can also use the kmem_cache_debug_flags() static key check for improved performance in kernels without the hardening and with debugging not enabled on boot. [1] https://lore.kernel.org/r/20200608230654.828134-18-guro@fb.com Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-10-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slub: extend checks guarded by slub_debug static keyVlastimil Babka2020-08-071-3/+3
| | | | | | | | | | | | | | | | | | | | | | There are few more places in SLUB that could benefit from reduced overhead of the static key introduced by a previous patch: - setup_object_debug() called on each object in newly allocated slab page - setup_page_debug() called on newly allocated slab page - __free_slab() called on freed slab page Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-9-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slub: introduce kmem_cache_debug_flags()Vlastimil Babka2020-08-071-5/+16
| | | | | | | | | | | | | | | | | | | | | | | | | There are few places that call kmem_cache_debug(s) (which tests if any of debug flags are enabled for a cache) immediately followed by a test for a specific flag. The compiler can probably eliminate the extra check, but we can make the code nicer by introducing kmem_cache_debug_flags() that works like kmem_cache_debug() (including the static key check) but tests for specific flag(s). The next patches will add more users. [vbabka@suse.cz: change return from int to bool, per Kees. Add VM_WARN_ON_ONCE() for invalid flags, per Roman] Link: http://lkml.kernel.org/r/949b90ed-e0f0-07d7-4d21-e30ec0958a7c@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Jann Horn <jannh@google.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-8-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slub: introduce static key for slub_debug()Vlastimil Babka2020-08-071-3/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | One advantage of CONFIG_SLUB_DEBUG is that a generic distro kernel can be built with the option enabled, but it's inactive until simply enabled on boot, without rebuilding the kernel. With a static key, we can further eliminate the overhead of checking whether a cache has a particular debug flag enabled if we know that there are no such caches (slub_debug was not enabled during boot). We use the same mechanism also for e.g. page_owner, debug_pagealloc or kmemcg functionality. This patch introduces the static key and makes the general check for per-cache debug flags kmem_cache_debug() use it. This benefits several call sites, including (slow path but still rather frequent) __slab_free(). The next patches will add more uses. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-7-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, slub: make reclaim_account attribute read-onlyVlastimil Babka2020-08-071-10/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The attribute reflects the SLAB_RECLAIM_ACCOUNT cache flag. It's not clear why this attribute was writable in the first place, as it's tied to how the cache is used by its creator, it's not a user tunable. Furthermore: - it affects slab merging, but that's not being checked while toggled - if affects whether __GFP_RECLAIMABLE flag is used to allocate page, but the runtime toggle doesn't update allocflags - it affects cache_vmstat_idx() so runtime toggling might lead to incosistency of NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE Thus make it read-only. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Roman Gushchin <guro@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-6-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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