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authorWill Deacon <will@kernel.org>2020-05-26 18:33:01 +0100
committerDavid S. Miller <davem@davemloft.net>2020-06-02 18:45:51 -0700
commit60bccaa671bce7ed040d9511b0738ca3b0a0e9ff (patch)
tree4cd661ce17ab6ea6cd8cda944a81335b78fa32f7 /mm/Kconfig
parent454b0289c6b5f2c66164654b80212d15fbef7a03 (diff)
downloadlinux-60bccaa671bce7ed040d9511b0738ca3b0a0e9ff.tar.bz2
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 <davem@davemloft.net> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig4
1 files changed, 4 insertions, 0 deletions
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