v3 changes: - fix missing hunk in patch 5/7 - more verbose cover letter and patch 6/7 commit log v2 changes: - shorten cache names to kmalloc-rcl-<SIZE> - last patch shortens <SIZE> for all kmalloc caches to e.g. "1k", "4M" - include dma caches to the 2D kmalloc_caches[] array to avoid a branch - vmstat counter nr_indirectly_reclaimable_bytes renamed to nr_kernel_misc_reclaimable, doesn't include kmalloc-rcl-* - /proc/meminfo counter renamed to KReclaimable, includes kmalloc-rcl* and nr_kernel_misc_reclaimable
Hi, as discussed at LSF/MM [1] here's a patchset that introduces kmalloc-reclaimable caches (more details in the second patch) and uses them for SLAB freelists and dcache external names. The latter allows us to repurpose the NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series. With patch 4/7, dcache external names are allocated from kmalloc-rcl-* caches, eliminating the need for manual accounting. More importantly, it also ensures the reclaimable kmalloc allocations are grouped in pages separate from the regular kmalloc allocations. The need for proper accounting of dcache external names has shown it's easy for misbehaving process to allocate lots of them, causing premature OOMs. Without the added grouping, it's likely that a similar workload can interleave the dcache external names allocations with regular kmalloc allocations (note: I haven't searched myself for an example of such regular kmalloc allocation, but I would be very surprised if there wasn't some). A pathological case would be e.g. one 64byte regular allocations with 63 external dcache names in a page (64x64=4096), which means the page is not freed even after reclaiming after all dcache names, and the process can thus "steal" the whole page with single 64byte allocation. If there other kmalloc users similar to dcache external names become identified, they can also benefit from the new functionality simply by adding __GFP_RECLAIMABLE to the kmalloc calls. Side benefits of the patchset (that could be also merged separately) include removed branch for detecting __GFP_DMA kmalloc(), and shortening kmalloc cache names in /proc/slabinfo output. The latter is potentially an ABI break in case there are tools parsing the names and expecting the values to be in bytes. This is how /proc/slabinfo looks like after booting in virtme: ... kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0 ... kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0 kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0 kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0 kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0 kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0 kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0 ... /proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter: ... nr_slab_reclaimable 2817 nr_slab_unreclaimable 1781 ... nr_kernel_misc_reclaimable 0 ... /proc/meminfo with new KReclaimable counter: ... Shmem: 564 kB KReclaimable: 11260 kB Slab: 18368 kB SReclaimable: 11260 kB SUnreclaim: 7108 kB KernelStack: 1248 kB ... Thanks, Vlastimil Vlastimil Babka (7): mm, slab: combine kmalloc_caches and kmalloc_dma_caches mm, slab/slub: introduce kmalloc-reclaimable caches mm, slab: allocate off-slab freelists as reclaimable when appropriate dcache: allocate external names from reclaimable kmalloc caches mm: rename and change semantics of nr_indirectly_reclaimable_bytes mm, proc: add KReclaimable to /proc/meminfo mm, slab: shorten kmalloc cache names for large sizes Documentation/filesystems/proc.txt | 4 + drivers/base/node.c | 19 ++-- drivers/staging/android/ion/ion_page_pool.c | 8 +- fs/dcache.c | 38 ++------ fs/proc/meminfo.c | 16 +-- include/linux/mmzone.h | 2 +- include/linux/slab.h | 49 +++++++--- mm/page_alloc.c | 19 ++-- mm/slab.c | 11 ++- mm/slab_common.c | 102 ++++++++++++-------- mm/slub.c | 13 +-- mm/util.c | 3 +- mm/vmstat.c | 6 +- 13 files changed, 161 insertions(+), 129 deletions(-) -- 2.18.0
