Just when I had decided that flush_cache_range() was always called with
a valid context,
Helge reported two cases where the "BUG_ON(!vma->vm_mm->context);" was
hit on the phantom
buildd:
[549700.051761] NET: Registered protocol family 38
[552929.287236] systemd-logind[1672]: New session 11638 of user root.
[555698.899355] ------------[ cut here ]------------
[555698.955264] kernel BUG at
/mnt/sdb6/linux/linux-4.15.4/arch/parisc/kernel/cache.c:587!
[555699.051275] CPU: 1 PID: 3254 Comm: kworker/1:2 Tainted: G D
4.15.0-1-parisc64-smp #1 Debian 4.15.4-1+b1
[555699.179274] Workqueue: events free_ioctx
[555699.247243] YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
[555699.303248] PSW: 00001000000001001111111100001111 Tainted: G D
[555699.391249] r00-03 000000ff0804ff0f 0000000040d22760
00000000404a6980 000000014a990b30
[555699.487249] r04-07 0000000040d01f60 00000000f40da000
00000000f40db000 00000041320c1ed8
[555699.583242] r08-11 000000014a9907e8 000000014a990728
000000014a990728 000000411617cd80
[555699.679256] r12-15 000000004107f150 0000000041080e48
0000000040d28760 0000000000000002
[555699.779246] r16-19 0000004133f50140 00000000f40da000
0000000066279900 00000000f40db000
[555699.875239] r20-23 00000000000044d5 fcfaa60000000000
000000014a990728 00000000f40db000
[555699.971239] r24-27 00000000f40db000 00000000f40da000
0000000008478800 0000000040d01f60
[555700.067237] r28-31 0000000007ac0000 000000014a990b00
000000014a990bd0 0000000000001000
[555700.167238] sr00-03 0000000007ac0000 0000000007ac0000
0000000007ac0000 0000000007ac0000
[555700.263236] sr04-07 0000000000000000 0000000000000000
0000000000000000 0000000000000000
[555700.379234] IASQ: 0000000000000000 0000000000000000 IAOQ:
000000004021c0b4 000000004021c0b8
[555700.483234] IIR: 03ffe01f ISR: 0000000000000000 IOR:
0000000000000000
[555700.567233] CPU: 1 CR30: 000000014a990000 CR31:
ffffffffffffffff
[555700.647233] ORIG_R28: 0000000040d01f60
[555700.695237] IAOQ[0]: flush_cache_range+0x164/0x168
[555700.755237] IAOQ[1]: flush_cache_page+0x0/0x1c8
[555700.811240] RP(r2): unmap_page_range+0xae8/0xb88
[555700.867231] Backtrace:
[555700.899249] [<00000000404a6980>] unmap_page_range+0xae8/0xb88
[555700.971238] [<00000000404a6ae0>] unmap_single_vma+0xc0/0x188
[555701.039238] [<00000000404a6cdc>] zap_page_range_single+0x134/0x1f8
[555701.115240] [<00000000404a702c>] unmap_mapping_range+0x1cc/0x208
[555701.191238] [<0000000040461518>] truncate_pagecache+0x98/0x108
[555701.263239] [<0000000040461624>] truncate_setsize+0x9c/0xb8
[555701.331263] [<00000000405d7f30>] put_aio_ring_file+0x80/0x100
[555701.403238] [<00000000405d803c>] aio_free_ring+0x8c/0x290
[555701.467236] [<00000000405d82c0>] free_ioctx+0x80/0x180
[555701.531287] [<0000000040284e6c>] process_one_work+0x21c/0x668
[555701.603237] [<00000000402854c4>] worker_thread+0x20c/0x778
[555701.671235] [<0000000040291d44>] kthread+0x2d4/0x2e0
[555701.735235] [<0000000040204020>] end_fault_vector+0x20/0xc0
This indicates that we need to handle the no context case in
flush_cache_range() as we do in
flush_cache_mm().
In thinking about this, I realized that we don't need to flush the TLB
when there is no context.
So, I added context checks to the large flush cases in flush_cache_mm()
and flush_cache_range().
The large flush case occurs frequently in flush_cache_mm() and the
change should improve fork
performance.
The v2 version of this change removes the BUG_ON from flush_cache_page()
by skipping the TLB flush
when there is no context. I also added code to flush the TLB in
flush_cache_mm() and flush_cache_range()
when we have a context that's not current. Now all three routines
handle TLB flushes in a similar manner.
Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index 79089778725b..e3b45546d589 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -543,7 +543,8 @@ void flush_cache_mm(struct mm_struct *mm)
rp3440, etc. So, avoid it if the mm isn't too big. */
if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) &&
mm_total_size(mm) >= parisc_cache_flush_threshold) {
- flush_tlb_all();
+ if (mm->context)
+ flush_tlb_all();
flush_cache_all();
return;
}
@@ -571,6 +572,8 @@ void flush_cache_mm(struct mm_struct *mm)
pfn = pte_pfn(*ptep);
if (!pfn_valid(pfn))
continue;
+ if (unlikely(mm->context))
+ flush_tlb_page(vma, addr);
__flush_cache_page(vma, addr, PFN_PHYS(pfn));
}
}
@@ -579,26 +582,46 @@ void flush_cache_mm(struct mm_struct *mm)
void flush_cache_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
+ pgd_t *pgd;
+ unsigned long addr;
+
if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) &&
end - start >= parisc_cache_flush_threshold) {
- flush_tlb_range(vma, start, end);
+ if (vma->vm_mm->context)
+ flush_tlb_range(vma, start, end);
flush_cache_all();
return;
}
- flush_user_dcache_range_asm(start, end);
- if (vma->vm_flags & VM_EXEC)
- flush_user_icache_range_asm(start, end);
- flush_tlb_range(vma, start, end);
+ if (vma->vm_mm->context == mfsp(3)) {
+ flush_user_dcache_range_asm(start, end);
+ if (vma->vm_flags & VM_EXEC)
+ flush_user_icache_range_asm(start, end);
+ flush_tlb_range(vma, start, end);
+ return;
+ }
+
+ pgd = vma->vm_mm->pgd;
+ for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
+ unsigned long pfn;
+ pte_t *ptep = get_ptep(pgd, addr);
+ if (!ptep)
+ continue;
+ pfn = pte_pfn(*ptep);
+ if (pfn_valid(pfn)) {
+ if (unlikely(vma->vm_mm->context))
+ flush_tlb_page(vma, addr);
+ __flush_cache_page(vma, addr, PFN_PHYS(pfn));
+ }
+ }
}
void
flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long pfn)
{
- BUG_ON(!vma->vm_mm->context);
-
if (pfn_valid(pfn)) {
- flush_tlb_page(vma, vmaddr);
+ if (likely(vma->vm_mm->context))
+ flush_tlb_page(vma, vmaddr);
__flush_cache_page(vma, vmaddr, PFN_PHYS(pfn));
}
}
