From 94fb9334182284e8e7e4bcb9125c25dc33af19d4 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 10 Jun 2015 17:49:42 +0200 Subject: [PATCH] x86/crash: Allocate enough low memory when crashkernel=high MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When the crash kernel is loaded above 4GiB in memory, the first kernel allocates only 72MiB of low-memory for the DMA requirements of the second kernel. On systems with many devices this is not enough and causes device driver initialization errors and failed crash dumps. Testing by SUSE and Redhat has shown that 256MiB is a good default value for now and the discussion has lead to this value as well. So set this default value to 256MiB to make sure there is enough memory available for DMA. Signed-off-by: Joerg Roedel [ Reflow comment. ] Signed-off-by: Borislav Petkov Acked-by: Baoquan He Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Young Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jörg Rödel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vivek Goyal Cc: kexec@lists.infradead.org Link: http://lkml.kernel.org/r/1433500202-25531-4-git-send-email-joro@8bytes.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/setup.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index d74ac33290ae..cba828892790 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -531,12 +531,14 @@ static void __init reserve_crashkernel_low(void) if (ret != 0) { /* * two parts from lib/swiotlb.c: - * swiotlb size: user specified with swiotlb= or default. - * swiotlb overflow buffer: now is hardcoded to 32k. - * We round it to 8M for other buffers that - * may need to stay low too. + * -swiotlb size: user-specified with swiotlb= or default. + * + * -swiotlb overflow buffer: now hardcoded to 32k. We round it + * to 8M for other buffers that may need to stay low too. Also + * make sure we allocate enough extra low memory so that we + * don't run out of DMA buffers for 32-bit devices. */ - low_size = swiotlb_size_or_default() + (8UL<<20); + low_size = max(swiotlb_size_or_default() + (8UL<<20), 256UL<<20); auto_set = true; } else { /* passed with crashkernel=0,low ? */ -- 2.39.2