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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: 298fa1ad55 ("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
This commit is contained in:
Thomas Gleixner 2020-11-12 11:59:32 +01:00
parent 13f876ba77
commit 2a656cad33
1 changed files with 13 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
mm/highmem.c
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@ -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)) {
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;
}