sparc32: mm: Disable SPLIT_PTLOCK_CPUS (60bccaa6) · Commits · 戴 / test

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 <davem@davemloft.net> Signed-off-by:

Will Deacon <will@kernel.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

mm/Kconfig

+4 −0

Original line number	Diff line number	Diff line
		@@ -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

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