This looks like something that Linus should be involved in too. He's been critical in the past about stack usage. On Wed, 28 May 2014 15:53:59 +0900 Minchan Kim <minchan@xxxxxxxxxx> wrote: > While I play inhouse patches with much memory pressure on qemu-kvm, > 3.14 kernel was randomly crashed. The reason was kernel stack overflow. > > When I investigated the problem, the callstack was a little bit deeper > by involve with reclaim functions but not direct reclaim path. > > I tried to diet stack size of some functions related with alloc/reclaim > so did a hundred of byte but overflow was't disappeard so that I encounter > overflow by another deeper callstack on reclaim/allocator path. > > Of course, we might sweep every sites we have found for reducing > stack usage but I'm not sure how long it saves the world(surely, > lots of developer start to add nice features which will use stack > agains) and if we consider another more complex feature in I/O layer > and/or reclaim path, it might be better to increase stack size( > meanwhile, stack usage on 64bit machine was doubled compared to 32bit > while it have sticked to 8K. Hmm, it's not a fair to me and arm64 > already expaned to 16K. ) > > So, my stupid idea is just let's expand stack size and keep an eye > toward stack consumption on each kernel functions via stacktrace of ftrace. > For example, we can have a bar like that each funcion shouldn't exceed 200K > and emit the warning when some function consumes more in runtime. > Of course, it could make false positive but at least, it could make a > chance to think over it. > > I guess this topic was discussed several time so there might be > strong reason not to increase kernel stack size on x86_64, for me not > knowing so Ccing x86_64 maintainers, other MM guys and virtio > maintainers. I agree with Boris that if this goes in, it should be a config option. Or perhaps selected by those file systems that need it. I hate to have 16K stacks on a box that doesn't have that much memory, but also just uses ext2. -- Steve > > [ 1065.604404] kworker/-5766 0d..2 1071625990us : stack_trace_call: Depth Size Location (51 entries) > [ 1065.604404] ----- ---- -------- > [ 1065.604404] kworker/-5766 0d..2 1071625991us : stack_trace_call: 0) 7696 16 lookup_address+0x28/0x30 > [ 1065.604404] kworker/-5766 0d..2 1071625991us : stack_trace_call: 1) 7680 16 _lookup_address_cpa.isra.3+0x3b/0x40 > [ 1065.604404] kworker/-5766 0d..2 1071625991us : stack_trace_call: 2) 7664 24 __change_page_attr_set_clr+0xe0/0xb50 > [ 1065.604404] kworker/-5766 0d..2 1071625991us : stack_trace_call: 3) 7640 392 kernel_map_pages+0x6c/0x120 > [ 1065.604404] kworker/-5766 0d..2 1071625992us : stack_trace_call: 4) 7248 256 get_page_from_freelist+0x489/0x920 > [ 1065.604404] kworker/-5766 0d..2 1071625992us : stack_trace_call: 5) 6992 352 __alloc_pages_nodemask+0x5e1/0xb20 > [ 1065.604404] kworker/-5766 0d..2 1071625992us : stack_trace_call: 6) 6640 8 alloc_pages_current+0x10f/0x1f0 > [ 1065.604404] kworker/-5766 0d..2 1071625992us : stack_trace_call: 7) 6632 168 new_slab+0x2c5/0x370 > [ 1065.604404] kworker/-5766 0d..2 1071625992us : stack_trace_call: 8) 6464 8 __slab_alloc+0x3a9/0x501 > [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 9) 6456 80 __kmalloc+0x1cb/0x200 > [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 10) 6376 376 vring_add_indirect+0x36/0x200 > [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 11) 6000 144 virtqueue_add_sgs+0x2e2/0x320 > [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 12) 5856 288 __virtblk_add_req+0xda/0x1b0 > [ 1065.604404] kworker/-5766 0d..2 1071625993us : stack_trace_call: 13) 5568 96 virtio_queue_rq+0xd3/0x1d0 > [ 1065.604404] kworker/-5766 0d..2 1071625994us : stack_trace_call: 14) 5472 128 __blk_mq_run_hw_queue+0x1ef/0x440 > [ 1065.604404] kworker/-5766 0d..2 1071625994us : stack_trace_call: 15) 5344 16 blk_mq_run_hw_queue+0x35/0x40 > [ 1065.604404] kworker/-5766 0d..2 1071625994us : stack_trace_call: 16) 5328 96 blk_mq_insert_requests+0xdb/0x160 > [ 1065.604404] kworker/-5766 0d..2 1071625994us : stack_trace_call: 17) 5232 112 blk_mq_flush_plug_list+0x12b/0x140 > [ 1065.604404] kworker/-5766 0d..2 1071625994us : stack_trace_call: 18) 5120 112 blk_flush_plug_list+0xc7/0x220 > [ 1065.604404] kworker/-5766 0d..2 1071625995us : stack_trace_call: 19) 5008 64 io_schedule_timeout+0x88/0x100 > [ 1065.604404] kworker/-5766 0d..2 1071625995us : stack_trace_call: 20) 4944 128 mempool_alloc+0x145/0x170 > [ 1065.604404] kworker/-5766 0d..2 1071625995us : stack_trace_call: 21) 4816 96 bio_alloc_bioset+0x10b/0x1d0 > [ 1065.604404] kworker/-5766 0d..2 1071625995us : stack_trace_call: 22) 4720 48 get_swap_bio+0x30/0x90 > [ 1065.604404] kworker/-5766 0d..2 1071625995us : stack_trace_call: 23) 4672 160 __swap_writepage+0x150/0x230 > [ 1065.604404] kworker/-5766 0d..2 1071625996us : stack_trace_call: 24) 4512 32 swap_writepage+0x42/0x90 > [ 1065.604404] kworker/-5766 0d..2 1071625996us : stack_trace_call: 25) 4480 320 shrink_page_list+0x676/0xa80 > [ 1065.604404] kworker/-5766 0d..2 1071625996us : stack_trace_call: 26) 4160 208 shrink_inactive_list+0x262/0x4e0 > [ 1065.604404] kworker/-5766 0d..2 1071625996us : stack_trace_call: 27) 3952 304 shrink_lruvec+0x3e1/0x6a0 > [ 1065.604404] kworker/-5766 0d..2 1071625996us : stack_trace_call: 28) 3648 80 shrink_zone+0x3f/0x110 > [ 1065.604404] kworker/-5766 0d..2 1071625997us : stack_trace_call: 29) 3568 128 do_try_to_free_pages+0x156/0x4c0 > [ 1065.604404] kworker/-5766 0d..2 1071625997us : stack_trace_call: 30) 3440 208 try_to_free_pages+0xf7/0x1e0 > [ 1065.604404] kworker/-5766 0d..2 1071625997us : stack_trace_call: 31) 3232 352 __alloc_pages_nodemask+0x783/0xb20 > [ 1065.604404] kworker/-5766 0d..2 1071625997us : stack_trace_call: 32) 2880 8 alloc_pages_current+0x10f/0x1f0 > [ 1065.604404] kworker/-5766 0d..2 1071625997us : stack_trace_call: 33) 2872 200 __page_cache_alloc+0x13f/0x160 > [ 1065.604404] kworker/-5766 0d..2 1071625998us : stack_trace_call: 34) 2672 80 find_or_create_page+0x4c/0xb0 > [ 1065.604404] kworker/-5766 0d..2 1071625998us : stack_trace_call: 35) 2592 80 ext4_mb_load_buddy+0x1e9/0x370 > [ 1065.604404] kworker/-5766 0d..2 1071625998us : stack_trace_call: 36) 2512 176 ext4_mb_regular_allocator+0x1b7/0x460 > [ 1065.604404] kworker/-5766 0d..2 1071625998us : stack_trace_call: 37) 2336 128 ext4_mb_new_blocks+0x458/0x5f0 > [ 1065.604404] kworker/-5766 0d..2 1071625998us : stack_trace_call: 38) 2208 256 ext4_ext_map_blocks+0x70b/0x1010 > [ 1065.604404] kworker/-5766 0d..2 1071625999us : stack_trace_call: 39) 1952 160 ext4_map_blocks+0x325/0x530 > [ 1065.604404] kworker/-5766 0d..2 1071625999us : stack_trace_call: 40) 1792 384 ext4_writepages+0x6d1/0xce0 > [ 1065.604404] kworker/-5766 0d..2 1071625999us : stack_trace_call: 41) 1408 16 do_writepages+0x23/0x40 > [ 1065.604404] kworker/-5766 0d..2 1071625999us : stack_trace_call: 42) 1392 96 __writeback_single_inode+0x45/0x2e0 > [ 1065.604404] kworker/-5766 0d..2 1071625999us : stack_trace_call: 43) 1296 176 writeback_sb_inodes+0x2ad/0x500 > [ 1065.604404] kworker/-5766 0d..2 1071626000us : stack_trace_call: 44) 1120 80 __writeback_inodes_wb+0x9e/0xd0 > [ 1065.604404] kworker/-5766 0d..2 1071626000us : stack_trace_call: 45) 1040 160 wb_writeback+0x29b/0x350 > [ 1065.604404] kworker/-5766 0d..2 1071626000us : stack_trace_call: 46) 880 208 bdi_writeback_workfn+0x11c/0x480 > [ 1065.604404] kworker/-5766 0d..2 1071626000us : stack_trace_call: 47) 672 144 process_one_work+0x1d2/0x570 > [ 1065.604404] kworker/-5766 0d..2 1071626000us : stack_trace_call: 48) 528 112 worker_thread+0x116/0x370 > [ 1065.604404] kworker/-5766 0d..2 1071626001us : stack_trace_call: 49) 416 240 kthread+0xf3/0x110 > [ 1065.604404] kworker/-5766 0d..2 1071626001us : stack_trace_call: 50) 176 176 ret_from_fork+0x7c/0xb0 > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > arch/x86/include/asm/page_64_types.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h > index 8de6d9cf3b95..678205195ae1 100644 > --- a/arch/x86/include/asm/page_64_types.h > +++ b/arch/x86/include/asm/page_64_types.h > @@ -1,7 +1,7 @@ > #ifndef _ASM_X86_PAGE_64_DEFS_H > #define _ASM_X86_PAGE_64_DEFS_H > > -#define THREAD_SIZE_ORDER 1 > +#define THREAD_SIZE_ORDER 2 > #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER) > #define CURRENT_MASK (~(THREAD_SIZE - 1)) > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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