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- 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
- @@ -115,6 +115,13 @@ 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;
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