Messages in this thread | | | Subject | RE: [RFC PATCH] dcache: give a chance to yield in shrink_dentry_list | From | Biscuit Ninja <> | Date | Thu, 14 Jul 2016 12:12:56 +0100 |
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> A softlockup in shrink_dentry_list when called from shrink_dcache_sb > was observed on a very busy server. It's possible that the list > passed to shrink_dentry_list is so big that it takes a while to > dispose of all entries. Adding a simple cond_resched would give > the cpu a chance to do some other useful work and no trip the > softlockup watchdog.
Hello Nikolay,
I'm interested in your proposed patch because I believe I've come across the same issue a handful of times, typically:
WARNING: CPU: 0 PID: 22717 at /build/buildd/linux-lts-trusty-3.13.0/fs/dcache.c:362 d_shrink_del +0x79/0x90() Modules linked in: pcnet32 mii vmwgfx ttm drm psmouse lp i2c_piix4 ppdev parport_pc vmw_vmci shpchp serio_raw mac_hid vmw_balloon parport floppy mptspi mptscsih mptbase e1000 vmw_pvscsi vmxnet3 CPU: 0 PID: 22717 Comm: sh Not tainted 3.13.0-32-generic #57~precise1-Ubuntu Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 10/22/2013 000000000000016a ffff88000616bbe8 ffffffff81752c9e 0000000000000007 0000000000000000 ffff88000616bc28 ffffffff8106af7c ffff88000616bc08 ffff880037f54480 ffff880037f54480 ffff880037f54500 ffff880037f544d8 Call Trace: [<ffffffff81752c9e>] dump_stack+0x46/0x58 [<ffffffff8106af7c>] warn_slowpath_common+0x8c/0xc0 [<ffffffff8106afca>] warn_slowpath_null+0x1a/0x20 [<ffffffff811df419>] d_shrink_del+0x79/0x90 [<ffffffff811e0ad2>] shrink_dentry_list+0x62/0xe0 [<ffffffff811e0c18>] shrink_dcache_parent+0x28/0x70 [<ffffffff812321c7>] proc_flush_task_mnt.isra.15+0x77/0x170 [<ffffffff812356e6>] proc_flush_task+0x56/0x70 [<ffffffff8106c803>] release_task+0x33/0x130 [<ffffffff8106cdcf>] wait_task_zombie+0x4cf/0x5f0 [<ffffffff8106cffb>] wait_consider_task.part.8+0x10b/0x180 [<ffffffff8106d0d5>] wait_consider_task+0x65/0x70 [<ffffffff8106d1e1>] do_wait+0x101/0x260 [<ffffffff8106e213>] SyS_wait4+0xa3/0x100 [<ffffffff8106bc10>] ? task_stopped_code+0x50/0x50 [<ffffffff8176847f>] tracesys+0xe1/0xe6 ---[ end trace e2a4a7d8b698f0ea ]--- BUG: soft lockup - CPU#0 stuck for 22s! [sh:22717] Modules linked in: pcnet32 mii vmwgfx ttm drm psmouse lp i2c_piix4 ppdev parport_pc vmw_vmci shpchp serio_raw mac_hid vmw_balloon parport floppy mptspi mptscsih mptbase e1000 vmw_pvscsi vmxnet3 CPU: 0 PID: 22717 Comm: sh Tainted: G W 3.13.0-32-generic #57~precise1-Ubuntu Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 10/22/2013 task: ffff88001ef717f0 ti: ffff88000616a000 task.ti: ffff88000616a000 RIP: 0010:[<ffffffff8175f28c>] [<ffffffff8175f28c>] _raw_spin_lock +0x1c/0x50 RSP: 0018:ffff88000616bc58 EFLAGS: 00000246
This is under Ubuntu 12.04.5 with kernel 3.13.0-32-generic.
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