openwrtv3/target/linux/generic/pending-4.9/100-MIPS-fix-cache-flushing-for-highmem-pages.patch
John Crispin 74d00a8c38 kernel: split patches folder up into backport, pending and hack folders
* properly format/comment all patches
* merge debloat patches
* merge Kconfig patches
* merge swconfig patches
* merge hotplug patches
* drop 200-fix_localversion.patch - upstream
* drop 222-arm_zimage_none.patch - unused
* drop 252-mv_cesa_depends.patch - no longer required
* drop 410-mtd-move-forward-declaration-of-struct-mtd_info.patch - unused
* drop 661-fq_codel_keep_dropped_stats.patch - outdated
* drop 702-phy_add_aneg_done_function.patch - upstream
* drop 840-rtc7301.patch - unused
* drop 841-rtc_pt7c4338.patch - upstream
* drop 921-use_preinit_as_init.patch - unused
* drop spio-gpio-old and gpio-mmc - unused

Signed-off-by: John Crispin <john@phrozen.org>
2017-08-05 08:46:36 +02:00

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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
@@ -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;