From 313a5257b84c26b7f080c5d294aabe7d38ca439c Mon Sep 17 00:00:00 2001 From: Stafford Horne Date: Thu, 25 Jun 2020 20:29:17 -0700 Subject: openrisc: fix boot oops when DEBUG_VM is enabled Since v5.8-rc1 OpenRISC Linux fails to boot when DEBUG_VM is enabled. This has been bisected to commit 42fc541404f2 ("mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()"). The added locking checks exposed the issue that OpenRISC was not taking this mmap lock when during page walks for DMA operations. This patch locks and unlocks the mmap lock for page walking. Link: http://lkml.kernel.org/r/20200617090247.1680188-1-shorne@gmail.com Fixes: 42fc541404f2 ("mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()" Signed-off-by: Stafford Horne Reviewed-by: Michel Lespinasse Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: Jason Gunthorpe Cc: Steven Price Cc: Thomas Hellstrom Cc: Robin Murphy Cc: Vlastimil Babka Cc: Daniel Jordan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/openrisc/kernel/dma.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch') diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c index c152a68811dd..345727638d52 100644 --- a/arch/openrisc/kernel/dma.c +++ b/arch/openrisc/kernel/dma.c @@ -74,8 +74,11 @@ void *arch_dma_set_uncached(void *cpu_addr, size_t size) * We need to iterate through the pages, clearing the dcache for * them and setting the cache-inhibit bit. */ + mmap_read_lock(&init_mm); error = walk_page_range(&init_mm, va, va + size, &set_nocache_walk_ops, NULL); + mmap_read_unlock(&init_mm); + if (error) return ERR_PTR(error); return cpu_addr; @@ -85,9 +88,11 @@ void arch_dma_clear_uncached(void *cpu_addr, size_t size) { unsigned long va = (unsigned long)cpu_addr; + mmap_read_lock(&init_mm); /* walk_page_range shouldn't be able to fail here */ WARN_ON(walk_page_range(&init_mm, va, va + size, &clear_nocache_walk_ops, NULL)); + mmap_read_unlock(&init_mm); } void arch_sync_dma_for_device(phys_addr_t addr, size_t size, -- cgit v1.2.3