From: Michael Ellerman mpe@ellerman.id.au
commit 6f07048c00fd100ed8cab66c225c157e0b6c0a50 upstream.
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 cai@lca.pw Reported-by: ppc syzbot c/o Andrew Donnellan ajd@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Daniel Axtens dja@axtens.net Link: https://lore.kernel.org/r/87lfs4f7d6.fsf@dja-thinkpad.axtens.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/include/asm/sections.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/arch/powerpc/include/asm/sections.h +++ b/arch/powerpc/include/asm/sections.h @@ -5,8 +5,22 @@
#include <linux/elf.h> #include <linux/uaccess.h> + +#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed + #include <asm-generic/sections.h>
+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__