mm/highmem: Take kmap_high_get() properly into account (2a656cad) · Commits · 戴 / test

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: ("highmem: Provide generic variant of kmap_atomic*") Reported-by:

<vtolkm@googlemail.com> Reported-by:

Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Tested-by:

Marek Szyprowski <m.szyprowski@samsung.com> Tested-by:

Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Link: https://lore.kernel.org/r/87y2j6n8mj.fsf@nanos.tec.linutronix.de

mm/highmem.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -426,12 +426,15 @@ 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)
		@@ -491,10 +494,14 @@ void kunmap_local_indexed(void *vaddr)

		if (addr < __fix_to_virt(FIX_KMAP_END) \|\|
		addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
		/*
		* 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);

		/* Handle mappings which were obtained by kmap_high_get() */
		kmap_high_unmap_local(addr);
		return;
		}

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