linux_dsm_epyc7002/arch/parisc/kernel
John David Anglin 01ab605704 parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results
The increased use of pdtlb/pitlb instructions seemed to increase the
frequency of random segmentation faults building packages. Further, we
had a number of cases where TLB inserts would repeatedly fail and all
forward progress would stop. The Haskell ghc package caused a lot of
trouble in this area. The final indication of a race in pte handling was
this syslog entry on sibaris (C8000):

 swap_free: Unused swap offset entry 00000004
 BUG: Bad page map in process mysqld  pte:00000100 pmd:019bbec5
 addr:00000000ec464000 vm_flags:00100073 anon_vma:0000000221023828 mapping: (null) index:ec464
 CPU: 1 PID: 9176 Comm: mysqld Not tainted 4.0.0-2-parisc64-smp #1 Debian 4.0.5-1
 Backtrace:
  [<0000000040173eb0>] show_stack+0x20/0x38
  [<0000000040444424>] dump_stack+0x9c/0x110
  [<00000000402a0d38>] print_bad_pte+0x1a8/0x278
  [<00000000402a28b8>] unmap_single_vma+0x3d8/0x770
  [<00000000402a4090>] zap_page_range+0xf0/0x198
  [<00000000402ba2a4>] SyS_madvise+0x404/0x8c0

Note that the pte value is 0 except for the accessed bit 0x100. This bit
shouldn't be set without the present bit.

It should be noted that the madvise system call is probably a trigger for many
of the random segmentation faults.

In looking at the kernel code, I found the following problems:

1) The pte_clear define didn't take TLB lock when clearing a pte.
2) We didn't test pte present bit inside lock in exception support.
3) The pte and tlb locks needed to merged in order to ensure consistency
between page table and TLB. This also has the effect of serializing TLB
broadcasts on SMP systems.

The attached change implements the above and a few other tweaks to try
to improve performance. Based on the timing code, TLB purges are very
slow (e.g., ~ 209 cycles per page on rp3440). Thus, I think it
beneficial to test the split_tlb variable to avoid duplicate purges.
Probably, all PA 2.0 machines have combined TLBs.

I dropped using __flush_tlb_range in flush_tlb_mm as I realized all
applications and most threads have a stack size that is too large to
make this useful. I added some comments to this effect.

Since implementing 1 through 3, I haven't had any random segmentation
faults on mx3210 (rp3440) in about one week of building code and running
as a Debian buildd.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: Helge Deller <deller@gmx.de>
2015-07-10 21:47:47 +02:00
..
.gitignore parisc: add arch/parisc/kernel/.gitignore 2008-10-10 16:32:28 +00:00
asm-offsets.c arch: Remove exec_domain from remaining archs 2015-04-12 21:03:30 +02:00
audit.c parisc: add kernel audit feature 2013-11-07 22:27:20 +01:00
binfmt_elf32.c parisc: fix redefinition of SET_PERSONALITY 2013-03-02 20:15:28 +01:00
cache.c parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results 2015-07-10 21:47:47 +02:00
compat_audit.c parisc: add kernel audit feature 2013-11-07 22:27:20 +01:00
drivers.c parisc/PCI: Use dev_is_pci() to identify PCI devices 2013-12-11 16:53:12 -07:00
entry.S parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results 2015-07-10 21:47:47 +02:00
firmware.c parisc: delete __cpuinit usage from all users 2013-07-14 19:36:51 -04:00
ftrace.c parisc: ftrace: Remove check of obsolete variable function_trace_stop 2014-07-18 13:57:05 -04:00
hardware.c parisc: add serial ports of C8000/1GHz machine to hardware database 2014-07-13 15:51:58 +02:00
head.S parisc: expose number of page table levels on Kconfig level 2015-04-14 16:49:02 -07:00
hpmc.S parisc: fix partly 16/64k PAGE_SIZE boot 2013-05-06 23:08:32 +02:00
inventory.c parisc: Fix interrupt routing for C8000 serial ports 2013-07-31 23:42:32 +02:00
irq.c parisc: fix up obsolete cpu function usage. 2015-03-05 15:25:08 +10:30
Makefile parisc: add kernel audit feature 2013-11-07 22:27:20 +01:00
module.c mm: vmalloc: pass additional vm_flags to __vmalloc_node_range() 2015-02-13 21:21:42 -08:00
pa7300lc.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pacache.S parisc: Use unshadowed index register for flush instructions in flush_dcache_page_asm and flush_icache_page_asm 2013-06-18 20:29:10 +02:00
parisc_ksyms.c parisc: Provide __ucmpdi2 to resolve undefined references in 32 bit builds. 2013-04-25 22:36:15 +02:00
pci-dma.c parisc: use for_each_sg() 2015-06-24 17:49:40 -07:00
pci.c parisc: provide pci_mmap_page_range() for parisc 2013-06-18 20:29:08 +02:00
pdc_chassis.c parisc: single_open() leaks 2013-05-05 00:10:41 -04:00
pdc_cons.c parisc: don't use module_init for non-modular core pdc_cons code 2015-06-16 14:12:30 -04:00
perf_asm.S Revert "parisc: fix trivial section name warnings" 2008-06-13 10:49:45 -04:00
perf_images.h [PARISC] Use kzalloc and other janitor-style cleanups 2006-01-22 20:26:31 -05:00
perf.c parisc64: don't use module_init for non-modular core perf code 2015-06-16 14:12:30 -04:00
process.c parisc: copy_thread(): rename 'arg' argument to 'kthread_arg' 2015-04-24 13:45:55 +02:00
processor.c parisc: delete __cpuinit usage from all users 2013-07-14 19:36:51 -04:00
ptrace.c Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
real2.S parisc: move pdc_result to real2.S 2008-10-10 16:32:28 +00:00
setup.c parisc: correctly display number of active CPUs 2013-11-07 22:29:05 +01:00
signal32.c constify copy_siginfo_to_user{,32}() 2013-11-09 00:16:29 -05:00
signal32.h constify copy_siginfo_to_user{,32}() 2013-11-09 00:16:29 -05:00
signal.c parisc: hpux - Remove hpux gateway page 2015-02-16 22:35:06 +01:00
smp.c parisc: Remove unused function 2015-02-17 10:41:19 +01:00
stacktrace.c parisc: add LATENCYTOP_SUPPORT and CONFIG_STACKTRACE_SUPPORT 2009-03-31 02:51:34 +00:00
sys_parisc32.c parisc: drop unused defines and header includes 2014-07-13 15:56:12 +02:00
sys_parisc.c parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures 2015-05-12 22:03:44 +02:00
syscall_table.S parisc: Add compile-time check when adding new syscalls 2015-03-23 10:57:25 +01:00
syscall.S parisc: Implement new LWS CAS supporting 64 bit operations. 2014-09-13 22:40:48 +02:00
time.c parisc: move definition of PAGE0 to asm/page.h 2012-05-10 15:12:08 -07:00
topology.c parisc: Replace NR_CPUS in parisc code 2009-01-05 19:09:02 +00:00
traps.c parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results 2015-07-10 21:47:47 +02:00
unaligned.c parisc: show number of FPE and unaligned access handler calls in /proc/interrupts 2013-05-24 22:35:26 +02:00
unwind.c parisc: use kernel_text_address() in unwind functions 2013-11-30 22:08:54 +01:00
vmlinux.lds.S parisc: fix kernel memory layout in vmlinux.ld.S 2013-11-30 22:09:21 +01:00