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Message-ID: <87wnh648ec.fsf@yhuang6-desk2.ccr.corp.intel.com> Date: Mon, 07 Mar 2022 13:51:55 +0800 From: "Huang, Ying" <ying.huang@...el.com> To: Qian Cai <quic_qiancai@...cinc.com> Cc: <linux-kernel@...r.kernel.org>, <linux-tip-commits@...r.kernel.org>, "Peter Zijlstra (Intel)" <peterz@...radead.org>, <x86@...nel.org>, <linux-arm-kernel@...ts.infradead.org> Subject: Re: [tip: sched/core] sched/numa: Avoid migrating task to CPU-less node Hi, Qian, "Huang, Ying" <ying.huang@...el.com> writes: > Qian Cai <quic_qiancai@...cinc.com> writes: > >> On Thu, Feb 17, 2022 at 06:56:52PM -0000, tip-bot2 for Huang Ying wrote: >>> The following commit has been merged into the sched/core branch of tip: >>> >>> Commit-ID: 5c7b1aaf139dab5072311853bacc40fc3457d1f9 >>> Gitweb: https://git.kernel.org/tip/5c7b1aaf139dab5072311853bacc40fc3457d1f9 >>> Author: Huang Ying <ying.huang@...el.com> >>> AuthorDate: Mon, 14 Feb 2022 20:15:53 +08:00 >>> Committer: Peter Zijlstra <peterz@...radead.org> >>> CommitterDate: Wed, 16 Feb 2022 15:57:53 +01:00 >>> >>> sched/numa: Avoid migrating task to CPU-less node >>> >>> In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA >>> nodes. But if the number of the hint page faults on a PMEM node is >>> the max for a task, The current NUMA balancing policy may try to place >>> the task on the PMEM node instead of DRAM node. This is unreasonable, >>> because there's no CPU in PMEM NUMA nodes. To fix this, CPU-less >>> nodes are ignored when searching the migration target node for a task >>> in this patch. >>> >>> To test the patch, we run a workload that accesses more memory in PMEM >>> node than memory in DRAM node. Without the patch, the PMEM node will >>> be chosen as preferred node in task_numa_placement(). While the DRAM >>> node will be chosen instead with the patch. >>> >>> Signed-off-by: "Huang, Ying" <ying.huang@...el.com> >>> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> >>> Link: https://lkml.kernel.org/r/20220214121553.582248-2-ying.huang@intel.com >> >> Reverting this commit on the top of today's linux-next fixed a boot crash >> on arm64 NUMA systems. >> >> Unable to handle kernel paging request at virtual address ffff7a6601694aec >> KASAN: maybe wild-memory-access in range [0xffffd3300b4a5760-0xffffd3300b4a5767] >> Mem abort info: >> ESR = 0x96000005 >> EC = 0x25: DABT (current EL), IL = 32 bits >> mlx5_core 0007:02:00.0: enabling device (0100 -> 0102) >> SET = 0, FnV = 0 >> EA = 0, S1PTW = 0 >> FSC = 0x05: level 1 translation fault >> Data abort info: >> ISV = 0, ISS = 0x00000005 >> CM = 0, WnR = 0 >> swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000400b3d6c6000 >> [ffff7a6601694aec] pgd=0000403fc007f003, p4d=0000403fc007f003, pud=0000000000000000 >> Internal error: Oops: 96000005 [#1] PREEMPT SMP >> Modules linked in: nouveau(+) drm_ttm_helper ttm nvme(+) drm_dp_helper drm_kms_helper mlx5_core(+) mpt3sas(+) xhci_pci(+) nvme_core raid_class xhci_pci_renesas drm >> CPU: 85 PID: 1308 Comm: udevadm Not tainted 5.17.0-rc6-next-20220301 #1 >> pstate: 40400009 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> pc : task_numa_placement >> lr : task_numa_placement >> sp : ffff800031047760 >> x29: ffff800031047760 x28: ffff3fffab916c00 x27: 0000000000000020 >> x26: 0000000000000001 x25: 0000000000000000 x24: 0000000000000000 >> >> x23: ffff07ffe5289a80 x22: ffffd3300b4a5760 x21: 000000000000003f >> x20: ffffd32feb4a5768 x19: 0000000000000000 x18: ffff07ffe528ad88 >> x17: ffffd32fe5693a1c x16: 0000000000000000 x15: ffff8000310478e0 >> >> x14: ffff07ffe528ad90 x13: 0000000000000002 x12: dfff80000000000d >> x11: 0000000000000001 x10: 000000000000b6be x9 : 0000000000000000 >> x8 : 00000000ffffffff x7 : ffffd32feb4a5780 x6 : 0000000000000000 >> x5 : 0000000000000000 x4 : 0000000000000000 x3 : 1ffffa6601694aec >> x2 : 0000000000000000 x1 : dfff800000000000 x0 : 000000001ffffff8 >> Call trace: >> task_numa_placement >> arch_test_bit at include/asm-generic/bitops/non-atomic.h:118 >> (inlined by) node_state at include/linux/nodemask.h:416 >> (inlined by) task_numa_placement at kernel/sched/fair.c:2439 >> task_numa_fault >> do_numa_page >> handle_pte_fault >> __handle_mm_fault >> handle_mm_fault >> do_page_fault >> do_translation_fault >> do_mem_abort >> el0_da >> el0t_64_sync_handler >> el0t_64_sync >> Code: 8b000296 d2d00001 f2fbffe1 d343fec3 (38e16861) >> ---[ end trace 0000000000000000 ]--- >> Kernel panic - not syncing: Oops: Fatal exception >> SMP: stopping secondary CPUs >> Kernel Offset: 0x532fdcf70000 from 0xffff800008000000 >> PHYS_OFFSET: 0x80000000 >> CPU features: 0x00,00042c0c,19801c82 >> Memory Limit: none >> ---[ end Kernel panic - not syncing: Oops: Fatal exception ]--- > > Thanks for reporting! Can you try whether the following debug patch can fix the issue? > > Best Regards, > Huang, Ying > > ----------------------------8<------------------------------------------- > From 176d185426730111e763eb386d0210561f021dbc Mon Sep 17 00:00:00 2001 > From: Huang Ying <ying.huang@...el.com> > Date: Wed, 2 Mar 2022 08:54:01 +0800 > Subject: [PATCH] dbg KASAN error > > --- > kernel/sched/fair.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index a3f0ea216ccb..1fe7a4510cca 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -2405,7 +2405,7 @@ static void task_numa_placement(struct task_struct *p) > } > > /* Cannot migrate task to CPU-less node */ > - if (!node_state(max_nid, N_CPU)) { > + if (max_nid != NUMA_NO_NODE && !node_state(max_nid, N_CPU)) { > int near_nid = max_nid; > int distance, near_distance = INT_MAX; Do you have time to give this patch a try? Best Regards, Huang, Ying
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