When we do ltp test using large swap,we get the following error: [34196.558224] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [34196.566010] float_exp_log D 0 16985 16971 0x00004000 [34196.571462] Stack : 900000010a33bdd8 0000000000027100 900000027417d680 900000010dfc3778 [34196.579421] 006200ca00000054 0000000000000004 000000fff424c000 9000000276ba8060 [34196.587378] 0000000000000002 90000000014bdfa0 0000000000000000 9000000276ba8000 [34196.595358] 900000010da17dd0 9000000276ba8068 9000000276ba8060 0000000000000002 [34196.603313] 900000010dfc3778 9000000000c1df80 ffffffffffffffff 9000000000c2170c [34196.611269] 0000000000000001 900000010a33bdc0 900000010a177dd0 900000010da17dd0 [34196.619224] 900000010a692d80 000000ff00000001 9000000276ba8060 900000010a33bea0 [34196.627180] 900000010a692d80 000000fff424ce04 9000000276ba8060 9000000000c20b3c [34196.635135] 0000000000000070 9000000000c23a24 000000000000003a fffffffffffffffb [34196.643090] 000000fff365c8b0 000000fff365e8f0 0000000128259020 0000000128259130 [34196.651045] ... [34196.653469] Call Trace: [34196.655902] [<9000000000c1d7ac>] __schedule+0x4b4/0xc5c [34196.661094] [<9000000000c1df7c>] schedule+0x28/0x7c [34196.665940] [<9000000000c21708>] rwsem_down_read_failed+0xfc/0x164 [34196.672082] [<9000000000c20b38>] down_read+0x50/0x58 [34196.677013] [<9000000000c23a20>] do_page_fault+0xf4/0x58c [34196.682380] [<9000000000218220>] tlb_do_page_fault_0+0x110/0x128 ... ... [34198.279088] Sending NMI from CPU 2 to CPUs 0-1,3: [34198.283761] NMI backtrace for cpu 1 [34198.283763] NMI backtrace for cpu 3 [34198.283764] NMI backtrace for cpu 0 [34198.283767] CPU: 3 PID: 940 Comm: Xorg Not tainted 4.19.190+ #1 [34198.283769] CPU: 0 PID: 1555 Comm: genload Not tainted 4.19.190+ #1 [34198.283770] Hardware name: Loongson LM-LS3A5000-7A1000-1w-V01-pc_A2101/LM-LS3A5000-7A1000-1w-V01-pc_A2101, BIOS KL.4.1H.LM.D.028.220624.R 06/24/2022 [34198.283770] $ 0 : 0000000000000000 90000000002465a4 9000000270e4c000 9000000270e4f220 [34198.283773] $ 4 : 0000000000000001 0000000002f41000 900000026a8b1d40 9000000270e4f158 [34198.283775] $ 8 : 0000000000000040 900000010aa9e798 0000000000000a00 00000000000000e1 [34198.283776] $12 : 00000000000000b0 0000000000000004 0000000000000020 9000000276b66480 [34198.283778] $16 : 900000000600ebf0 000000000000000b 0000000000002523 9000000000c30e30 [34198.283780] $20 : 00000000eac0c6e6 90000000014485b8 9000000000fdff00 0000000000000000 [34198.283781] $24 : 900000026d317840 fffffffffffffff5 0000000000000040 900000027d0fbe00 [34198.283783] $28 : 0000000000000000 0000000000000001 90000000010ceb10 0000000000000000 [34198.283789] era : 90000000002465bc mod_delayed_work_on+0x84/0xac [34198.283790] ra : 90000000002465a4 mod_delayed_work_on+0x6c/0xac [34198.283791] CSR crmd: 00000040 [34198.283791] CSR prmd: 00000004 [34198.283792] CSR ecfg: 00071fff [34198.283793] CSR estat: 9000000000fdff00 [34198.283793] CSR euen: 900000026d317840 [34198.283795] ExcCode : 3d (SubCode 3) [34198.283796] PrId : 0014c011 (Loongson-64bit) [34198.283797] CPU: 0 PID: 1555 Comm: genload Not tainted 4.19.190+ #1 [34198.283798] Hardware name: Loongson LM-LS3A5000-7A1000-1w-V01-pc_A2101/LM-LS3A5000-7A1000-1w-V01-pc_A2101, BIOS KL.4.1H.LM.D.028.220624.R 06/24/2022 [34198.283799] Stack : 0000000000000000 9000000000c16888 9000000270e4c000 900000027c167df0 [34198.283800] 0000000000000000 900000027c167df0 0000000000000000 900000000149d310 [34198.283802] 0000000000000040 90000000014a7f80 0000000000000000 0000000000000088 [34198.283804] 9000000000c16888 0000000000000007 0000000000000006 0000000000000007 [34198.283805] 9000000006000768 000002cccd7c4b02 3032322e3832302e 363020522e343236 [34198.283807] 00000000000003f3 0000000004bc4000 9000000000fdff00 ffff800000000000 [34198.283808] 90000000010bb500 0000000000000000 0000000000000000 9000000000204f54 [34198.283809] 9000000000ea53c0 0000000000000001 90000000010ceb10 0000000000000000 [34198.283811] 9000000000209628 000000fff6cb38e8 00000000000000b0 0000000000000004 [34198.283812] 0000000000000000 0000000000071fff 0000000000000000 90000000010bb500 [34198.283814] ... [34198.283815] Call Trace: [34198.283817] [<9000000000209628>] show_stack+0x34/0x13c [34198.283820] [<9000000000c16884>] dump_stack+0x98/0xd0 [34198.283822] [<9000000000bfe430>] nmi_cpu_backtrace+0xe0/0xe8 [34198.283823] [<9000000000204f68>] handle_backtrace+0x14/0x48 [34198.283827] [<90000000002d8524>] flush_smp_call_function_queue+0xac/0x194 [34198.283829] [<900000000020255c>] loongson3_ipi_interrupt+0xd4/0xec [34198.283831] [<90000000002034f0>] except_vec_vi_handler+0xac/0xdc [34198.283833] [<90000000002465bc>] mod_delayed_work_on+0x84/0xac [34198.283837] [<90000000006c3e74>] kblockd_mod_delayed_work_on+0x24/0x34 [34198.283841] [<90000000006d4d88>] blk_mq_run_hw_queue+0xb0/0x128 [34198.283843] [<90000000006d7a80>] blk_mq_flush_plug_list+0x178/0x29c [34198.283846] [<90000000006c9884>] blk_flush_plug_list+0xf0/0x298 [34198.283848] [<900000000025d1bc>] io_schedule_prepare+0x40/0x58 [34198.283850] [<9000000000c1e4fc>] io_schedule+0x14/0x40 [34198.283853] [<9000000000704dc0>] wbt_wait+0x1b0/0x374 [34198.283856] [<90000000006ebb30>] rq_qos_throttle+0x44/0x68 [34198.283858] [<90000000006d7100>] blk_mq_make_request+0xd8/0x580 [34198.283860] [<90000000006c74d4>] generic_make_request+0x11c/0x330 [34198.283862] [<90000000006c77f8>] submit_bio+0x110/0x180 [34198.283865] [<90000000003faa04>] __swap_writepage+0x174/0x434 [34198.283868] [<90000000003b73cc>] pageout.isra.10+0x144/0x3d8 [34198.283870] [<90000000003b9918>] shrink_page_list+0x7a8/0xe94 [34198.283871] [<90000000003ba984>] shrink_inactive_list+0x248/0x70c [34198.283873] [<90000000003bb5bc>] shrink_node_memcg+0x1fc/0x748 [34198.283874] [<90000000003bbbdc>] shrink_node+0xd4/0x4b8 [34198.283875] [<90000000003bc0a8>] do_try_to_free_pages+0xe8/0x3c0 [34198.283877] [<90000000003bc45c>] try_to_free_pages+0xdc/0x23c [34198.283880] [<90000000003a5c7c>] __alloc_pages_nodemask+0x5bc/0xffc [34198.283883] [<900000000040e314>] alloc_pages_vma+0x98/0x274 [34198.283886] [<90000000003e5698>] __handle_mm_fault+0xd3c/0x14f0 [34198.283887] [<90000000003e5f48>] handle_mm_fault+0xfc/0x248 [34198.283889] [<9000000000c23a78>] do_page_fault+0x14c/0x58c [34198.283890] [<9000000000218348>] tlb_do_page_fault_1+0x110/0x128 and we find out that it is because the __swap_writepage consumed too much time,so I think when call __swap_writepage to reclaim memory,it should complete ASAP. For the above case,we should not do write back throttle when a process other than kswapd is writing data to swap,because it may be reclaiming memory. Signed-off-by: Hongchen Zhang <zhanghongchen@xxxxxxxxxxx> --- block/blk-wbt.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index a998200..d6323d0 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -554,7 +554,9 @@ static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio) flags |= WBT_KSWAPD; if (bio_op(bio) == REQ_OP_DISCARD) flags |= WBT_DISCARD; - flags |= WBT_TRACKED; + if (current_is_kswapd() || + (bio->bi_end_io != end_swap_bio_write)) + flags |= WBT_TRACKED; } return flags; } -- 1.8.3.1
