On 2024-08-27 00:36, Charlie Jenkins wrote:
The hint address should not forcefully restrict the addresses returned
by mmap as this causes mmap to report ENOMEM when there is memory still
available.
Signed-off-by: Charlie Jenkins <[email protected]>
Fixes: b5b4287accd7 ("riscv: mm: Use hint address in mmap if available")
Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
Closes:
https://lore.kernel.org/linux-kernel/ZbxTNjQPFKBatMq+@ghost/T/#mccb1890466bf5a488c9ce7441e57e42271895765
---
arch/riscv/include/asm/processor.h | 26 ++------------------------
1 file changed, 2 insertions(+), 24 deletions(-)
diff --git a/arch/riscv/include/asm/processor.h
b/arch/riscv/include/asm/processor.h
index 8702b8721a27..efa1b3519b23 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -14,36 +14,14 @@
#include <asm/ptrace.h>
-/*
- * addr is a hint to the maximum userspace address that mmap should provide, so
- * this macro needs to return the largest address space available so that
- * mmap_end < addr, being mmap_end the top of that address space.
- * See Documentation/arch/riscv/vm-layout.rst for more details.
- */
#define arch_get_mmap_end(addr, len, flags) \
({ \
- unsigned long mmap_end; \
- typeof(addr) _addr = (addr); \
- if ((_addr) == 0 || is_compat_task() || \
- ((_addr + len) > BIT(VA_BITS - 1))) \
- mmap_end = STACK_TOP_MAX; \
- else \
- mmap_end = (_addr + len); \
- mmap_end; \
+ STACK_TOP_MAX; \
})
#define arch_get_mmap_base(addr, base) \
({ \
- unsigned long mmap_base; \
- typeof(addr) _addr = (addr); \
- typeof(base) _base = (base); \
- unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base); \
- if ((_addr) == 0 || is_compat_task() || \
- ((_addr + len) > BIT(VA_BITS - 1))) \
- mmap_base = (_base); \
- else \
- mmap_base = (_addr + len) - rnd_gap; \
- mmap_base; \
+ base; \
})
#ifdef CONFIG_64BIT
I tested this patch on 6.10.2 kernel and could confirm that it fixes the
crash of chromium. But I think I prefer Yangyu Chen's approach because
that would avoid breaking some applications on sv57.
Tested-by: Levi Zim <[email protected]> # Chromium, sv39
