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From ae5763668200f801524fc9d8976093ceb461df92 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 12 Nov 2020 11:59:32 +0100
Subject: [PATCH 061/296] mm/highmem: Take kmap_high_get() properly into
account
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.35-rt39.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 <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
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
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;
}
--
2.30.2
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