From 3df53841fc978eae47eb80dbb4ccaefa880589a7 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 12 Nov 2020 11:59:32 +0100 Subject: [PATCH 061/323] mm/highmem: Take kmap_high_get() properly into account Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz kunmap_local() warns when the virtual address to unmap is below PAGE_OFFSET. This is correct except for the case that the mapping was obtained via kmap_high_get() because the PKMAP addresses are right below PAGE_OFFSET. Cure it by skipping the WARN_ON() when the unmap was handled by kunmap_high(). Fixes: 298fa1ad5571 ("highmem: Provide generic variant of kmap_atomic*") Reported-by: vtolkm@googlemail.com Reported-by: Marek Szyprowski Signed-off-by: Thomas Gleixner Tested-by: Marek Szyprowski Tested-by: Sebastian Andrzej Siewior Cc: Andrew Morton Link: https://lore.kernel.org/r/87y2j6n8mj.fsf@nanos.tec.linutronix.de Signed-off-by: Sebastian Andrzej Siewior --- mm/highmem.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/mm/highmem.c b/mm/highmem.c index 8db577e5290c..72b9a2d95c72 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -422,12 +422,15 @@ static inline void *arch_kmap_local_high_get(struct page *page) #endif /* Unmap a local mapping which was obtained by kmap_high_get() */ -static inline void kmap_high_unmap_local(unsigned long vaddr) +static inline bool kmap_high_unmap_local(unsigned long vaddr) { #ifdef ARCH_NEEDS_KMAP_HIGH_GET - if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) + if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) { kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)])); + return true; + } #endif + return false; } static inline int kmap_local_calc_idx(int idx) @@ -493,10 +496,14 @@ void kunmap_local_indexed(void *vaddr) if (addr < __fix_to_virt(FIX_KMAP_END) || addr > __fix_to_virt(FIX_KMAP_BEGIN)) { - WARN_ON_ONCE(addr < PAGE_OFFSET); - - /* Handle mappings which were obtained by kmap_high_get() */ - kmap_high_unmap_local(addr); + /* + * Handle mappings which were obtained by kmap_high_get() + * first as the virtual address of such mappings is below + * PAGE_OFFSET. Warn for all other addresses which are in + * the user space part of the virtual address space. + */ + if (!kmap_high_unmap_local(addr)) + WARN_ON_ONCE(addr < PAGE_OFFSET); return; } -- 2.43.0