From 60bccaa671bce7ed040d9511b0738ca3b0a0e9ff Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 26 May 2020 18:33:01 +0100 Subject: sparc32: mm: Disable SPLIT_PTLOCK_CPUS The SRMMU page-table allocator is not compatible with SPLIT_PTLOCK_CPUS for two major reasons: 1. Pages are allocated via memblock, and therefore the ptl is not cleared by prep_new_page(), which is expected by ptlock_init() 2. Multiple PTE tables can exist in a single page, causing them to share the same ptl and deadlock when attempting to take the same lock twice (e.g. as part of copy_page_range()). Ensure that SPLIT_PTLOCK_CPUS is not selected for SPARC32. Cc: David S. Miller Signed-off-by: Will Deacon Signed-off-by: David S. Miller --- mm/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'mm') diff --git a/mm/Kconfig b/mm/Kconfig index c1acc34c1c35..97458119cce8 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -192,6 +192,9 @@ config MEMORY_HOTREMOVE # Default to 4 for wider testing, though 8 might be more appropriate. # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. +# SPARC32 allocates multiple pte tables within a single page, and therefore +# a per-page lock leads to problems when multiple tables need to be locked +# at the same time (e.g. copy_page_range()). # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. # config SPLIT_PTLOCK_CPUS @@ -199,6 +202,7 @@ config SPLIT_PTLOCK_CPUS default "999999" if !MMU default "999999" if ARM && !CPU_CACHE_VIPT default "999999" if PARISC && !PA20 + default "999999" if SPARC32 default "4" config ARCH_ENABLE_SPLIT_PMD_PTLOCK -- cgit v1.2.3-59-g8ed1b