Anonymous pages are allocated with the shared mappings colouring,
SHM_COLOUR. Since the alias boundary on machines with PA8800 and
PA8900 processors is unknown, flush_user_cache_page() might not
flush all mappings of a shared anonymous page. Flushing the whole
data cache flushes all mappings.
This won't fix all coherency issues with shared mappings but it
seems to work well in practice. I haven't seen any random memory
faults in almost a month on a rp3440 running as a debian buildd
machine.
There is a small preformance hit.
Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
---
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index 0fd04073d4b6..a20c1c47b780 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -722,7 +722,10 @@ void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned lon
return;
if (parisc_requires_coherency()) {
- flush_user_cache_page(vma, vmaddr);
+ if (vma->vm_flags & VM_SHARED)
+ flush_data_cache();
+ else
+ flush_user_cache_page(vma, vmaddr);
return;
}
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