From ee97347fe058d02035f354d59a5aa5aa6e1be4cc Mon Sep 17 00:00:00 2001 From: Hari Bathini Date: Tue, 22 Mar 2022 14:46:17 -0700 Subject: [PATCH] powerpc/fadump: opt out from freeing pages on cma activation failure With commit a4e92ce8e4c8 ("powerpc/fadump: Reservationless firmware assisted dump"), Linux kernel's Contiguous Memory Allocator (CMA) based reservation was introduced in fadump. That change was aimed at using CMA to let applications utilize the memory reserved for fadump while blocking it from being used for kernel pages. The assumption was, even if CMA activation fails for whatever reason, the memory still remains reserved to avoid it from being used for kernel pages. But commit 072355c1cf2d ("mm/cma: expose all pages to the buddy if activation of an area fails") breaks this assumption as it started exposing all pages to buddy allocator on CMA activation failure. It led to warning messages like below while running crash-utility on vmcore of a kernel having above two commits: crash: seek error: kernel virtual address: To fix this problem, opt out from exposing pages to buddy allocator on CMA activation failure for fadump reserved memory. Link: https://lkml.kernel.org/r/20220117075246.36072-3-hbathini@linux.ibm.com Signed-off-by: Hari Bathini Acked-by: David Hildenbrand Acked-by: Michael Ellerman Cc: Mahesh Salgaonkar Cc: Mike Kravetz Cc: Oscar Salvador Cc: Sourabh Jain Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/powerpc/kernel/fadump.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index 7eb67201ea41..4fdb7c77fda1 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -113,6 +113,12 @@ static int __init fadump_cma_init(void) } /* + * If CMA activation fails, keep the pages reserved, instead of + * exposing them to buddy allocator. Same as 'fadump=nocma' case. + */ + cma_reserve_pages_on_error(fadump_cma); + + /* * So we now have successfully initialized cma area for fadump. */ pr_info("Initialized 0x%lx bytes cma area at %ldMB from 0x%lx " -- 2.11.0