Revert "MIPS: make userspace mapping young by default"

This reverts commit f685a533a7fab35c5d069dcd663f59c8e4171a75.

The MIPS cache flush logic needs to know whether the mapping was already
established to decide how to flush caches.  This is done by checking the
valid bit in the PTE.  The commit above breaks this logic by setting the
valid in the PTE in new mappings, which causes kernel crashes.

Link: https://lkml.kernel.org/r/20210526094335.92948-1-tsbogend@alpha.franken.de
Fixes: f685a533a7f ("MIPS: make userspace mapping young by default")
Reported-by: Zhou Yanjie <zhouyanjie@wanyeetech.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Huang Pei <huangpei@loongson.cn>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 730daa00952b..f3ffab9b9e39 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2939,6 +2939,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		}
 		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
 		entry = mk_pte(new_page, vma->vm_page_prot);
+		entry = pte_sw_mkyoung(entry);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 
 		/*
@@ -3602,6 +3603,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	__SetPageUptodate(page);
 
 	entry = mk_pte(page, vma->vm_page_prot);
+	entry = pte_sw_mkyoung(entry);
 	if (vma->vm_flags & VM_WRITE)
 		entry = pte_mkwrite(pte_mkdirty(entry));
 
@@ -3786,6 +3788,8 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
 
 	if (prefault && arch_wants_old_prefaulted_pte())
 		entry = pte_mkold(entry);
+	else
+		entry = pte_sw_mkyoung(entry);
 
 	if (write)
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);