openwrt/target/linux/generic/pending-4.19/100-MIPS-fix-cache-flushing-for-highmem-pages.patch
Hauke Mehrtens 52a82ce3dd kernel: Copy patches from kernel 4.14 to 4.19
This just copies the files from the kernel 4.14 specific folders into
the kernel 4.19 specific folder, no changes are done to the files in
this commit.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
2018-12-15 12:50:06 +01:00

31 lines
886 B
Diff

From: Felix Fietkau <nbd@nbd.name>
Subject: MIPS: fix cache flushing for highmem pages
Most cache flush ops were no-op for highmem pages. This led to nasty
segfaults and (in the case of page_address(page) == NULL) kernel
crashes.
Fix this by always flushing highmem pages using kmap/kunmap_atomic
around the actual cache flush. This might be a bit inefficient, but at
least it's stable.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -116,6 +116,13 @@ void __flush_anon_page(struct page *page
{
unsigned long addr = (unsigned long) page_address(page);
+ if (PageHighMem(page)) {
+ addr = (unsigned long)kmap_atomic(page);
+ flush_data_cache_page(addr);
+ __kunmap_atomic((void *)addr);
+ return;
+ }
+
if (pages_do_alias(addr, vmaddr)) {
if (page_mapcount(page) && !Page_dcache_dirty(page)) {
void *kaddr;