Commit 2a656cad authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

mm/highmem: Take kmap_high_get() properly into account 



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: 298fa1ad ("highmem: Provide generic variant of kmap_atomic*")
Reported-by: default avatar <vtolkm@googlemail.com>
Reported-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Tested-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/87y2j6n8mj.fsf@nanos.tec.linutronix.de
parent 13f876ba

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;

	}