This is a note to let you know that I've just added the patch titled
parisc: Handle case where flush_cache_range is called with no context
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
parisc-handle-case-where-flush_cache_range-is-called-with-no-context.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9ef0f88fe5466c2ca1d2975549ba6be502c464c1 Mon Sep 17 00:00:00 2001
From: John David Anglin <dave.anglin@xxxxxxxx>
Date: Wed, 7 Mar 2018 08:18:05 -0500
Subject: parisc: Handle case where flush_cache_range is called with no context
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: John David Anglin <dave.anglin@xxxxxxxx>
commit 9ef0f88fe5466c2ca1d2975549ba6be502c464c1 upstream.
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:
kernel BUG at /mnt/sdb6/linux/linux-4.15.4/arch/parisc/kernel/cache.c:587!
CPU: 1 PID: 3254 Comm: kworker/1:2 Tainted: G D 4.15.0-1-parisc64-smp #1 Debian 4.15.4-1+b1
Workqueue: events free_ioctx
IAOQ[0]: flush_cache_range+0x164/0x168
IAOQ[1]: flush_cache_page+0x0/0x1c8
RP(r2): unmap_page_range+0xae8/0xb88
Backtrace:
[<00000000404a6980>] unmap_page_range+0xae8/0xb88
[<00000000404a6ae0>] unmap_single_vma+0xc0/0x188
[<00000000404a6cdc>] zap_page_range_single+0x134/0x1f8
[<00000000404a702c>] unmap_mapping_range+0x1cc/0x208
[<0000000040461518>] truncate_pagecache+0x98/0x108
[<0000000040461624>] truncate_setsize+0x9c/0xb8
[<00000000405d7f30>] put_aio_ring_file+0x80/0x100
[<00000000405d803c>] aio_free_ring+0x8c/0x290
[<00000000405d82c0>] free_ioctx+0x80/0x180
[<0000000040284e6c>] process_one_work+0x21c/0x668
[<00000000402854c4>] worker_thread+0x20c/0x778
[<0000000040291d44>] kthread+0x2d4/0x2e0
[<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>
Cc: stable@xxxxxxxxxxxxxxx # 4.9+
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/parisc/kernel/cache.c | 41 ++++++++++++++++++++++++++++++++---------
1 file changed, 32 insertions(+), 9 deletions(-)
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -542,7 +542,8 @@ 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;
}
@@ -570,6 +571,8 @@ 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));
}
}
@@ -596,26 +599,46 @@ flush_user_icache_range(unsigned long st
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));
}
}
Patches currently in stable-queue which might be from dave.anglin@xxxxxxxx are
queue-4.9/parisc-handle-case-where-flush_cache_range-is-called-with-no-context.patch