Commit e9ed22e6 authored Jun 18, 2022 by John David Anglin Committed by Helge Deller Jun 26, 2022

parisc: Fix flush_anon_page on PA8800/PA8900



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@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org   # v5.18+

parent d16c5c7c

arch/parisc/kernel/cache.c

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -722,6 +722,9 @@ void flush_anon_page(struct vm_area_struct vma, struct page page, unsigned lon
	return;		return;

	if (parisc_requires_coherency()) {		if (parisc_requires_coherency()) {
			if (vma->vm_flags & VM_SHARED)
			flush_data_cache();
			else
	flush_user_cache_page(vma, vmaddr);		flush_user_cache_page(vma, vmaddr);
	return;		return;
	}		}