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Subject[PATCH] RISC-V: Acquire mmap lock before invoking walk_page_range
Date
As per walk_page_range documentation, mmap lock should be acquired by the
caller before invoking walk_page_range. mmap_assert_locked gets triggered
without that. The details can be found here.

http://lists.infradead.org/pipermail/linux-riscv/2020-June/010335.html

Fixes: 395a21ff859c(riscv: add ARCH_HAS_SET_DIRECT_MAP support)
Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
arch/riscv/mm/pageattr.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index ec2c70f84994..289a9a5ea5b5 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -151,6 +151,7 @@ int set_memory_nx(unsigned long addr, int numpages)

int set_direct_map_invalid_noflush(struct page *page)
{
+ int ret;
unsigned long start = (unsigned long)page_address(page);
unsigned long end = start + PAGE_SIZE;
struct pageattr_masks masks = {
@@ -158,11 +159,16 @@ int set_direct_map_invalid_noflush(struct page *page)
.clear_mask = __pgprot(_PAGE_PRESENT)
};

- return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+ mmap_read_lock(&init_mm);
+ ret = walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+ mmap_read_unlock(&init_mm);
+
+ return ret;
}

int set_direct_map_default_noflush(struct page *page)
{
+ int ret;
unsigned long start = (unsigned long)page_address(page);
unsigned long end = start + PAGE_SIZE;
struct pageattr_masks masks = {
@@ -170,7 +176,11 @@ int set_direct_map_default_noflush(struct page *page)
.clear_mask = __pgprot(0)
};

- return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+ mmap_read_lock(&init_mm);
+ ret = walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+ mmap_read_unlock(&init_mm);
+
+ return ret;
}

void __kernel_map_pages(struct page *page, int numpages, int enable)
--
2.26.2
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