From: John David Anglin dave.anglin@bell.net
commit e9ed22e6e5010997a2f922eef61ca797d0a2a246 upstream.
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+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/parisc/kernel/cache.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -722,7 +722,10 @@ void flush_anon_page(struct vm_area_stru 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; }