From 5ebd4c22897dce65845807a9bd3a31cc4e142b53 Mon Sep 17 00:00:00 2001 From: Soeren Sandmann Date: Wed, 28 Oct 2009 18:55:36 +0100 Subject: highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow debug_kmap_atomic() tries to prevent ever printing more than 10 warnings, but it does so by testing whether an unsigned integer is equal to 0. However, if the warning is caused by a nested IRQ, then this counter may underflow and the stream of warnings will never end. Fix that by using a signed integer instead. Signed-off-by: Soeren Sandmann Pedersen Cc: Linus Torvalds Cc: a.p.zijlstra@chello.nl Cc: # .31.x LKML-Reference: Signed-off-by: Ingo Molnar --- mm/highmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/highmem.c b/mm/highmem.c index 25878cc..33587de 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -426,9 +426,9 @@ void __init page_address_init(void) void debug_kmap_atomic(enum km_type type) { - static unsigned warn_count = 10; + static int warn_count = 10; - if (unlikely(warn_count == 0)) + if (unlikely(warn_count < 0)) return; if (unlikely(in_interrupt())) { -- cgit v1.1 From d4515646699b6ad7b1a98ceb871296b957f3ef47 Mon Sep 17 00:00:00 2001 From: Soeren Sandmann Date: Wed, 28 Oct 2009 18:56:35 +0100 Subject: highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE Previously calling debug_kmap_atomic() with these types would cause spurious warnings. (triggered by SysProf using perf events) Signed-off-by: Soeren Sandmann Pedersen Cc: Linus Torvalds Cc: a.p.zijlstra@chello.nl Cc: # .31.x LKML-Reference: Signed-off-by: Ingo Molnar --- mm/highmem.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/highmem.c b/mm/highmem.c index 33587de..9c1e627 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -432,10 +432,15 @@ void debug_kmap_atomic(enum km_type type) return; if (unlikely(in_interrupt())) { - if (in_irq()) { + if (in_nmi()) { + if (type != KM_NMI && type != KM_NMI_PTE) { + WARN_ON(1); + warn_count--; + } + } else if (in_irq()) { if (type != KM_IRQ0 && type != KM_IRQ1 && type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ && - type != KM_BOUNCE_READ) { + type != KM_BOUNCE_READ && type != KM_IRQ_PTE) { WARN_ON(1); warn_count--; } @@ -452,7 +457,9 @@ void debug_kmap_atomic(enum km_type type) } if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ || - type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) { + type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ || + type == KM_IRQ_PTE || type == KM_NMI || + type == KM_NMI_PTE ) { if (!irqs_disabled()) { WARN_ON(1); warn_count--; -- cgit v1.1