From 2bf7c3efc393937d1e5f92681501a914dbfbae07 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Mon, 15 Jun 2015 16:15:44 -0400 Subject: [PATCH] sparc64: Convert BUG_ON to warning Pagefault handling has a BUG_ON path that panics the system. Convert it to a warning instead. There is no need to bring down the system for this kind of failure. The following was hit while running: perf sched record -g -- make -j 16 [3609412.782801] kernel BUG at /opt/dahern/linux.git/arch/sparc/mm/fault_64.c:416! [3609412.782833] \|/ ____ \|/ [3609412.782833] "@'/ .. \`@" [3609412.782833] /_| \__/ |_\ [3609412.782833] \__U_/ [3609412.782870] cat(4516): Kernel bad sw trap 5 [#1] [3609412.782889] CPU: 0 PID: 4516 Comm: cat Tainted: G E 4.1.0-rc8+ #6 [3609412.782909] task: fff8000126e31f80 ti: fff8000110d90000 task.ti: fff8000110d90000 [3609412.782931] TSTATE: 0000004411001603 TPC: 000000000096b164 TNPC: 000000000096b168 Y: 0000004e Tainted: G E [3609412.782964] TPC: [3609412.782979] g0: 000000000096abe0 g1: 0000000000d314c4 g2: 0000000000000000 g3: 0000000000000001 [3609412.783009] g4: fff8000126e31f80 g5: fff80001302d2000 g6: fff8000110d90000 g7: 00000000000000ff [3609412.783045] o0: 0000000000aff6a8 o1: 00000000000001a0 o2: 0000000000000001 o3: 0000000000000054 [3609412.783080] o4: fff8000100026820 o5: 0000000000000001 sp: fff8000110d935f1 ret_pc: 000000000096b15c [3609412.783117] RPC: [3609412.783137] l0: 000007feff996000 l1: 0000000000030001 l2: 0000000000000004 l3: fff8000127bd0120 [3609412.783174] l4: 0000000000000054 l5: fff8000127bd0188 l6: 0000000000000000 l7: fff8000110d9dba8 [3609412.783210] i0: fff8000110d93f60 i1: fff8000110ca5530 i2: 000000000000003f i3: 0000000000000054 [3609412.783244] i4: fff800010000081a i5: fff8000100000398 i6: fff8000110d936a1 i7: 0000000000407c6c [3609412.783286] I7: [3609412.783308] Call Trace: [3609412.783329] [0000000000407c6c] sparc64_realfault_common+0x10/0x20 [3609412.783353] Disabling lock debugging due to kernel taint [3609412.783379] Caller[0000000000407c6c]: sparc64_realfault_common+0x10/0x20 [3609412.783449] Caller[fff80001002283e4]: 0xfff80001002283e4 [3609412.783471] Instruction DUMP: 921021a0 7feaff91 901222a8 <91d02005> 82086100 02f87f7b 808a2873 81cfe008 01000000 [3609412.783542] Kernel panic - not syncing: Fatal exception [3609412.784605] Press Stop-A (L1-A) to return to the boot prom [3609412.784615] ---[ end Kernel panic - not syncing: Fatal exception With this patch rather than a panic I occasionally get something like this: perf sched record -g -m 1024 -- make -j N where N is based on number of cpus (128 to 1024 for a T7-4 and 8 for an 8 cpu VM on a T5-2). WARNING: CPU: 211 PID: 52565 at /opt/dahern/linux.git/arch/sparc/mm/fault_64.c:417 do_sparc64_fault+0x340/0x70c() address (7feffcd6000) != regs->tpc (fff80001004873c0) Modules linked in: ipt_REJECT nf_reject_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables ip6t_REJECT nf_reject_ipv6 xt_tcpudp nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables x_tables ipv6 cdc_ether usbnet mii ixgbe mdio igb i2c_algo_bit i2c_core ptp crc32c_sparc64 camellia_sparc64 des_sparc64 des_generic md5_sparc64 sha512_sparc64 sha1_sparc64 uio_pdrv_genirq uio usb_storage mpt3sas scsi_transport_sas raid_class aes_sparc64 sunvnet sunvdc sha256_sparc64(E) sha256_generic(E) CPU: 211 PID: 52565 Comm: ld Tainted: G W E 4.1.0-rc8+ #19 Call Trace: [000000000045ce30] warn_slowpath_common+0x7c/0xa0 [000000000045ceec] warn_slowpath_fmt+0x30/0x40 [000000000098ad64] do_sparc64_fault+0x340/0x70c [0000000000407c2c] sparc64_realfault_common+0x10/0x20 ---[ end trace 62ee02065a01a049 ]--- ld[52565]: segfault at fff80001004873c0 ip fff80001004873c0 (rpc fff8000100158868) sp 000007feffcd70e1 error 30002 in libc-2.12.so[fff8000100410000+184000] The segfault is horrible, but better than a system panic. An 8-cpu VM on a T5-2 also showed the above traces from time to time, so it is a general problem and not specific to the T7 or baremetal. Signed-off-by: David Ahern Signed-off-by: David S. Miller --- arch/sparc/mm/fault_64.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index e9268ea1a68d..dbabe5713a15 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -413,8 +413,9 @@ good_area: * that here. */ if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { - BUG_ON(address != regs->tpc); - BUG_ON(regs->tstate & TSTATE_PRIV); + WARN(address != regs->tpc, + "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc); + WARN_ON(regs->tstate & TSTATE_PRIV); goto bad_area; } -- 2.20.1