From 2a999aa0a10f4d0d9a57a06974df620f8a856239 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 29 Oct 2013 08:33:36 -0700 Subject: Kconfig: make KOBJECT_RELEASE debugging require timer debugging Without the timer debugging, the delayed kobject release will just result in undebuggable oopses if it triggers any latent bugs. That doesn't actually help debugging at all. So make DEBUG_KOBJECT_RELEASE depend on DEBUG_OBJECTS_TIMERS to avoid having people enable one without the other. Signed-off-by: Linus Torvalds --- lib/Kconfig.debug | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 06344d9..094f315 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -983,7 +983,7 @@ config DEBUG_KOBJECT config DEBUG_KOBJECT_RELEASE bool "kobject release debugging" - depends on DEBUG_KERNEL + depends on DEBUG_OBJECTS_TIMERS help kobjects are reference counted objects. This means that their last reference count put is not predictable, and the kobject can -- cgit v1.1 From 3d77b50c5874b7e923be946ba793644f82336b75 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 31 Oct 2013 16:34:17 -0700 Subject: lib/scatterlist.c: don't flush_kernel_dcache_page on slab page Commit b1adaf65ba03 ("[SCSI] block: add sg buffer copy helper functions") introduces two sg buffer copy helpers, and calls flush_kernel_dcache_page() on pages in SG list after these pages are written to. Unfortunately, the commit may introduce a potential bug: - Before sending some SCSI commands, kmalloc() buffer may be passed to block layper, so flush_kernel_dcache_page() can see a slab page finally - According to cachetlb.txt, flush_kernel_dcache_page() is only called on "a user page", which surely can't be a slab page. - ARCH's implementation of flush_kernel_dcache_page() may use page mapping information to do optimization so page_mapping() will see the slab page, then VM_BUG_ON() is triggered. Aaro Koskinen reported the bug on ARM/kirkwood when DEBUG_VM is enabled, and this patch fixes the bug by adding test of '!PageSlab(miter->page)' before calling flush_kernel_dcache_page(). Signed-off-by: Ming Lei Reported-by: Aaro Koskinen Tested-by: Simon Baatz Cc: Russell King - ARM Linux Cc: Will Deacon Cc: Aaro Koskinen Acked-by: Catalin Marinas Cc: FUJITA Tomonori Cc: Tejun Heo Cc: "James E.J. Bottomley" Cc: Jens Axboe Cc: [3.2+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/scatterlist.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/scatterlist.c b/lib/scatterlist.c index a685c8a..d16fa29 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -577,7 +577,8 @@ void sg_miter_stop(struct sg_mapping_iter *miter) miter->__offset += miter->consumed; miter->__remaining -= miter->consumed; - if (miter->__flags & SG_MITER_TO_SG) + if ((miter->__flags & SG_MITER_TO_SG) && + !PageSlab(miter->page)) flush_kernel_dcache_page(miter->page); if (miter->__flags & SG_MITER_ATOMIC) { -- cgit v1.1