From 6f07048c00fd100ed8cab66c225c157e0b6c0a50 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Wed, 27 Nov 2019 18:41:26 +1100 Subject: powerpc: Define arch_is_kernel_initmem_freed() for lockdep Under certain circumstances, we hit a warning in lockdep_register_key: if (WARN_ON_ONCE(static_obj(key))) return; This occurs when the key falls into initmem that has since been freed and can now be reused. This has been observed on boot, and under memory pressure. Define arch_is_kernel_initmem_freed(), which allows lockdep to correctly identify this memory as dynamic. This fixes a bug picked up by the powerpc64 syzkaller instance where we hit the WARN via alloc_netdev_mqs. Reported-by: Qian Cai Reported-by: ppc syzbot c/o Andrew Donnellan Signed-off-by: Michael Ellerman Signed-off-by: Daniel Axtens Link: https://lore.kernel.org/r/87lfs4f7d6.fsf@dja-thinkpad.axtens.net --- arch/powerpc/include/asm/sections.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h index 5a9b6eb651b6..d19871763ed4 100644 --- a/arch/powerpc/include/asm/sections.h +++ b/arch/powerpc/include/asm/sections.h @@ -5,8 +5,22 @@ #include #include + +#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed + #include +extern bool init_mem_is_free; + +static inline int arch_is_kernel_initmem_freed(unsigned long addr) +{ + if (!init_mem_is_free) + return 0; + + return addr >= (unsigned long)__init_begin && + addr < (unsigned long)__init_end; +} + extern char __head_end[]; #ifdef __powerpc64__ -- cgit v1.2.1