The previously submitted patch did not resolve the random segmentation faults observed on the phantom buildd system. There are still unresolved problems with the Debian 4.8 and 4.9 kernels on C8000. The attached patch removes the flush of the offset map pages and does a whole data cache flush for large ranges. No other arch flushes the offset map in these routines as far as I can tell. I have not observed any random segmentation faults on rp3440 in two weeks of testing with 4.10.0 and 4.10.1. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # v4.8+ Signed-off-by: Helge Deller <deller@gmx.de>
Pull parisc fixes and cleanups from Helge Deller: "Nothing really important in this patchset: fix resource leaks in error paths, coding style cleanups and code removal" * 'parisc-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Remove flush_user_dcache_range and flush_user_icache_range parisc: fix a printk parisc: ccio-dma: Handle return NULL error from ioremap_nocache parisc: Define access_ok() as macro parisc: eisa: Fix resource leaks in error paths parisc: eisa: Remove coding style errors
We are going to split more MM APIs out of <linux/sched.h>, which will have to be picked up from a couple of .c files. The APIs that we are going to move are: arch_pick_mmap_layout() arch_get_unmapped_area() arch_get_unmapped_area_topdown() mm_update_next_owner() Include the header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
The functions flush_user_dcache_range() and flush_user_icache_range() are only used by the parisc signal handling code. This code only needs to flush a couple of lines, so the threshold check is unnecessary overhead. Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
At bootup we run measurements to calculate the best threshold for when we should be using full TLB flushes instead of just flushing a specific amount of TLB entries. This performance test is run over the kernel text segment. But running this TLB performance test on the kernel text segment turned out to crash some SMP machines when the kernel text pages were mapped as huge pages. To avoid those crashes this patch simply skips this test on some SMP machines and calculates an optimal threshold based on the maximum number of available TLB entries and number of online CPUs. On a technical side, this seems to happen: The TLB measurement code uses flush_tlb_kernel_range() to flush specific TLB entries with a page size of 4k (pdtlb 0(sr1,addr)). On UP systems this purge instruction seems to work without problems even if the pages were mapped as huge pages. But on SMP systems the TLB purge instruction is broadcasted to other CPUs. Those CPUs then crash the machine because the page size is not as expected. C8000 machines with PA8800/PA8900 CPUs were not affected by this problem, because the required cache coherency prohibits to use huge pages at all. Sadly I didn't found any documentation about this behaviour, so this finding is purely based on testing with phyiscal SMP machines (A500-44 and J5000, both were 2-way boxes). Cc: <stable@vger.kernel.org> # v3.18+ Signed-off-by: Helge Deller <deller@gmx.de>
Helge reported to me the following startup crash:
[ 0.000000] Linux version 4.8.0-1-parisc64-smp (debian-kernel@lists.debian.org) (gcc version 5.4.1 20161019 (GCC) ) #1 SMP Debian 4.8.7-1 (2016-11-13)
[ 0.000000] The 64-bit Kernel has started...
[ 0.000000] Kernel default page size is 4 KB. Huge pages enabled with 1 MB physical and 2 MB virtual size.
[ 0.000000] Determining PDC firmware type: System Map.
[ 0.000000] model 9000/785/J5000
[ 0.000000] Total Memory: 2048 MB
[ 0.000000] Memory: 2018528K/2097152K available (9272K kernel code, 3053K rwdata, 1319K rodata, 1024K init, 840K bss, 78624K reserved, 0K cma-reserved)
[ 0.000000] virtual kernel memory layout:
[ 0.000000] vmalloc : 0x0000000000008000 - 0x000000003f000000 (1007 MB)
[ 0.000000] memory : 0x0000000040000000 - 0x00000000c0000000 (2048 MB)
[ 0.000000] .init : 0x0000000040100000 - 0x0000000040200000 (1024 kB)
[ 0.000000] .data : 0x0000000040b0e000 - 0x0000000040f533e0 (4372 kB)
[ 0.000000] .text : 0x0000000040200000 - 0x0000000040b0e000 (9272 kB)
[ 0.768910] Brought up 1 CPUs
[ 0.992465] NET: Registered protocol family 16
[ 2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000
[ 2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online
[ 2.726692] Setting cache flush threshold to 1024 kB
[ 2.729932] Not-handled unaligned insn 0x43ffff80
[ 2.798114] Setting TLB flush threshold to 140 kB
[ 2.928039] Unaligned handler failed, ret = -1
[ 3.000419] _______________________________
[ 3.000419] < Your System ate a SPARC! Gah! >
[ 3.000419] -------------------------------
[ 3.000419] \ ^__^
[ 3.000419] (__)\ )\/\
[ 3.000419] U ||----w |
[ 3.000419] || ||
[ 9.340055] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1
[ 9.448082] task: 00000000bfd48060 task.stack: 00000000bfd50000
[ 9.528040]
[ 10.760029] IASQ: 0000000000000000 0000000000000000 IAOQ: 000000004025d154 000000004025d158
[ 10.868052] IIR: 43ffff80 ISR: 0000000000340000 IOR: 000001ff54150960
[ 10.960029] CPU: 1 CR30: 00000000bfd50000 CR31: 0000000011111111
[ 11.052057] ORIG_R28: 000000004021e3b4
[ 11.100045] IAOQ[0]: irq_exit+0x94/0x120
[ 11.152062] IAOQ[1]: irq_exit+0x98/0x120
[ 11.208031] RP(r2): irq_exit+0xb8/0x120
[ 11.256074] Backtrace:
[ 11.288067] [<00000000402cd944>] cpu_startup_entry+0x1e4/0x598
[ 11.368058] [<0000000040109528>] smp_callin+0x2c0/0x2f0
[ 11.436308] [<00000000402b53fc>] update_curr+0x18c/0x2d0
[ 11.508055] [<00000000402b73b8>] dequeue_entity+0x2c0/0x1030
[ 11.584040] [<00000000402b3cc0>] set_next_entity+0x80/0xd30
[ 11.660069] [<00000000402c1594>] pick_next_task_fair+0x614/0x720
[ 11.740085] [<000000004020dd34>] __schedule+0x394/0xa60
[ 11.808054] [<000000004020e488>] schedule+0x88/0x118
[ 11.876039] [<0000000040283d3c>] rescuer_thread+0x4d4/0x5b0
[ 11.948090] [<000000004028fc4c>] kthread+0x1ec/0x248
[ 12.016053] [<0000000040205020>] end_fault_vector+0x20/0xc0
[ 12.092239] [<00000000402050c0>] _switch_to_ret+0x0/0xf40
[ 12.164044]
[ 12.184036] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1
[ 12.244040] Backtrace:
[ 12.244040] [<000000004021c480>] show_stack+0x68/0x80
[ 12.244040] [<00000000406f332c>] dump_stack+0xec/0x168
[ 12.244040] [<000000004021c74c>] die_if_kernel+0x25c/0x430
[ 12.244040] [<000000004022d320>] handle_unaligned+0xb48/0xb50
[ 12.244040]
[ 12.632066] ---[ end trace 9ca05a7215c7bbb2 ]---
[ 12.692036] Kernel panic - not syncing: Attempted to kill the idle task!
We have the insn 0x43ffff80 in IIR but from IAOQ we should have:
4025d150: 0f f3 20 df ldd,s r19(r31),r31
4025d154: 0f 9f 00 9c ldw r31(ret0),ret0
4025d158: bf 80 20 58 cmpb,*<> r0,ret0,4025d18c <irq_exit+0xcc>
Cpu0 has just completed running parisc_setup_cache_timing:
[ 2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000
[ 2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online
[ 2.726692] Setting cache flush threshold to 1024 kB
[ 2.729932] Not-handled unaligned insn 0x43ffff80
[ 2.798114] Setting TLB flush threshold to 140 kB
[ 2.928039] Unaligned handler failed, ret = -1
From the backtrace, cpu1 is in smp_callin:
void __init smp_callin(void)
{
int slave_id = cpu_now_booting;
smp_cpu_init(slave_id);
preempt_disable();
flush_cache_all_local(); /* start with known state */
flush_tlb_all_local(NULL);
local_irq_enable(); /* Interrupts have been off until now */
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
So, it has just flushed its caches and the TLB. It would seem either the
flushes in parisc_setup_cache_timing or smp_callin have corrupted kernel
memory.
The attached patch reworks parisc_setup_cache_timing to remove the races
in setting the cache and TLB flush thresholds. It also corrects the
number of bytes flushed in the TLB calculation.
The patch flushes the cache and TLB on cpu0 before starting the
secondary processors so that they are started from a known state.
Tested with a few reboots on c8000.
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>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Helge Deller <deller@gmx.de>
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>