linux/arch/sparc/mm
David Ahern 2bf7c3efc3 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: <do_sparc64_fault+0x5e4/0x6a0>
[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: <do_sparc64_fault+0x5dc/0x6a0>
[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: <sparc64_realfault_common+0x10/0x20>
[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 <david.ahern@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-06-25 06:01:02 -07:00
..
extable.c sparc: Add module.h to files previously implicitly using it. 2011-10-31 19:30:54 -04:00
fault_32.c mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler 2015-05-19 08:39:15 +02:00
fault_64.c sparc64: Convert BUG_ON to warning 2015-06-25 06:01:02 -07:00
gup.c mm: gup: use get_user_pages_unlocked within get_user_pages_fast 2015-02-11 17:06:05 -08:00
highmem.c sched/preempt, mm/kmap: Explicitly disable/enable preemption in kmap_atomic_* 2015-05-19 08:39:14 +02:00
hugetlbpage.c mm/hugetlb: reduce arch dependent code about huge_pmd_unshare 2015-06-24 17:49:41 -07:00
hypersparc.S [PATCH] sparc32: vm_area_struct access for old Sun SPARCs. 2013-07-10 13:56:10 -07:00
init_32.c sparc32: fix sparse warning in devices.c 2014-04-29 01:12:26 -04:00
init_64.c mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute 2015-06-24 17:49:44 -07:00
init_64.h sparc64: Use kernel page tables for vmemmap. 2014-10-05 16:53:39 -07:00
io-unit.c sparc32: fix sparse warning in io-unit.c 2014-05-18 19:01:26 -07:00
iommu.c sparc32: fix sparse warning in iommu.c 2014-05-18 19:01:26 -07:00
leon_mm.c sparc32: fix sparse "Should it be static?" in mm/ 2014-04-29 01:12:25 -04:00
Makefile sparc32: introduce run-time patching of srmmu access functions 2012-05-27 23:52:49 -07:00
mm_32.h sparc32: fix sparse "Should it be static?" in mm/ 2014-04-29 01:12:25 -04:00
srmmu_access.S sparc32: introduce run-time patching of srmmu access functions 2012-05-27 23:52:49 -07:00
srmmu.c sparc32: destroy_context() and switch_mm() needs to disable interrupts. 2014-12-18 12:47:54 -05:00
swift.S [PATCH] sparc32: vm_area_struct access for old Sun SPARCs. 2013-07-10 13:56:10 -07:00
tlb.c sparc: Replace __get_cpu_var uses 2014-08-26 13:45:55 -04:00
tsb.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next 2014-06-19 07:50:07 -10:00
tsunami.S [PATCH] sparc32: vm_area_struct access for old Sun SPARCs. 2013-07-10 13:56:10 -07:00
ultra.S sparc64: Make PAGE_OFFSET variable. 2013-11-12 15:22:34 -08:00
viking.S [PATCH] sparc32: vm_area_struct access for old Sun SPARCs. 2013-07-10 13:56:10 -07:00