Messages in this thread Patch in this message | | | Subject | [PATCH] make kobject dynamic allocation check use kallsyms_lookup() | From | Dave Hansen <> | Date | Wed, 22 Aug 2007 15:03:41 -0700 |
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One of the top ten sysfs problems is that users use statically allocated kobjects. This patch reminds them that this is a naughty thing.
One _really_ nice thing this patch does, is us the kallsyms mechanism to print out exactly which symbol is being complained about:
The kobject at, or inside 'statickobj.2'@(0xc040d020) is not dynamically allocated.
This patch replaces the previous implementation's use of a _sdata symbol in favor of using kallsyms_lookup(). If a kobject's address is a resolvable symbol, then it isn't dynamically allocated.
The one exception to this is init symbols. The patch also checks to see whether __init memory has been freed and if it has will allow kobjects in those sections.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com> ---
lxc-dave/arch/i386/kernel/vmlinux.lds.S | 2 -- lxc-dave/include/linux/init.h | 1 + lxc-dave/init/main.c | 9 +++++++++ lxc-dave/lib/kobject.c | 31 ++++++++++++++++++++++--------- 4 files changed, 32 insertions(+), 11 deletions(-)
diff -puN lib/kobject.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup lib/kobject.c --- lxc/lib/kobject.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700 +++ lxc-dave/lib/kobject.c 2007-08-22 14:51:50.000000000 -0700 @@ -139,23 +139,36 @@ static int ptr_in_range(void *ptr, void return 0; } -static void verify_dynamic_kobject_allocation(struct kobject *kobj) +void verify_dynamic_kobject_allocation(struct kobject *kobj) { - if (ptr_in_range(kobj, &_sdata[0], &_edata[0])) - goto warn; - if (ptr_in_range(kobj, &__bss_start[0], &__bss_stop[0])) - goto warn; - return; -warn: + char *namebuf; + const char *ret; + + namebuf = kzalloc(KSYM_NAME_LEN, GFP_KERNEL); + ret = kallsyms_lookup((unsigned long)kobj, NULL, NULL, NULL, + namebuf); + /* + * This is the X86_32-only part of this function. + * This is here because it is valid to have a kobject + * in an __init section, but only after those + * sections have been freed back to the dynamic pool. + */ + if (!initmem_now_dynamic && + ptr_in_range(kobj, __init_begin, __init_end)) + goto out; + if (!ret || !strlen(ret)) + goto out; pr_debug("---- begin silly warning ----\n"); pr_debug("This is a janitorial warning, not a kernel bug.\n"); #ifdef CONFIG_DEBUG_KOBJECT - print_symbol("The kobject at, or inside %s is not dynamically allocated.\n", - (unsigned long)kobj); + pr_debug("The kobject at, or inside '%s'@(0x%p) is not dynamically allocated.\n", + namebuf, kobj); #endif pr_debug("kobjects must be dynamically allocated, not static\n"); /* dump_stack(); */ pr_debug("---- end silly warning ----\n"); +out: + kfree(namebuf); } #else static void verify_dynamic_kobject_allocation(struct kobject *kobj) diff -L sre -puN /dev/null /dev/null diff -puN arch/i386/kernel/vmlinux.lds.S~make-kobject-allocation-debugging-check-use-kallsyms_lookup arch/i386/kernel/vmlinux.lds.S --- lxc/arch/i386/kernel/vmlinux.lds.S~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700 +++ lxc-dave/arch/i386/kernel/vmlinux.lds.S 2007-08-22 14:51:50.000000000 -0700 @@ -71,8 +71,6 @@ SECTIONS __tracedata_end = .; } - _sdata = .; /* End of text section */ - RODATA /* writeable */ diff -puN init/main.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup init/main.c --- lxc/init/main.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700 +++ lxc-dave/init/main.c 2007-08-22 14:51:50.000000000 -0700 @@ -771,12 +771,21 @@ static void run_init_process(char *init_ kernel_execve(init_filename, argv_init, envp_init); } +/* + * __init/__init_data sections are turned into normal + * dynamically allocated memory later in boot. When + * this is 0, the memory is for the __init purposes, + * when it it some other value, the memory is dynamic. + */ +int initmem_now_dynamic; + /* This is a non __init function. Force it to be noinline otherwise gcc * makes it inline to init() and it becomes part of init.text section */ static int noinline init_post(void) { free_initmem(); + initmem_now_dynamic = 1; unlock_kernel(); mark_rodata_ro(); system_state = SYSTEM_RUNNING; diff -puN lib/Makefile~make-kobject-allocation-debugging-check-use-kallsyms_lookup lib/Makefile diff -puN include/linux/kernel.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup include/linux/kernel.h diff -puN arch/i386/mm/init.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup arch/i386/mm/init.c diff -puN include/linux/init.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup include/linux/init.h --- lxc/include/linux/init.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700 +++ lxc-dave/include/linux/init.h 2007-08-22 14:51:50.000000000 -0700 @@ -83,6 +83,7 @@ extern initcall_t __security_initcall_st extern char __initdata boot_command_line[]; extern char *saved_command_line; extern unsigned int reset_devices; +extern int initmem_now_dynamic; /* used by init/main.c */ void setup_arch(char **); _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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