From ac2b86fdef5b44f194eefaa6b7b6aea9423d1bc2 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Fr=C3=A9d=C3=A9ric=20Weisbecker?= Date: Wed, 24 Sep 2008 16:31:56 +0100 Subject: [PATCH] x86/ftrace: use uaccess in atomic context With latest -tip I get this bug: [ 49.439988] in_atomic():0, irqs_disabled():1 [ 49.440118] INFO: lockdep is turned off. [ 49.440118] Pid: 2814, comm: modprobe Tainted: G W 2.6.27-rc7 #4 [ 49.440118] [] __might_sleep+0xe1/0x120 [ 49.440118] [] ftrace_modify_code+0x2a/0xd0 [ 49.440118] [] ? ftrace_test_p6nop+0x0/0xa [ 49.440118] [] __ftrace_update_code+0xfe/0x2f0 [ 49.440118] [] ? ftrace_test_p6nop+0x0/0xa [ 49.440118] [] ftrace_convert_nops+0x50/0x80 [ 49.440118] [] ftrace_init_module+0x16/0x20 [ 49.440118] [] load_module+0x185b/0x1d30 [ 49.440118] [] ? find_get_page+0x0/0xf0 [ 49.440118] [] ? sprintf+0x0/0x30 [ 49.440118] [] ? mutex_lock_interruptible_nested+0x1f2/0x350 [ 49.440118] [] sys_init_module+0x53/0x1b0 [ 49.440118] [] ? do_page_fault+0x0/0x740 [ 49.440118] [] syscall_call+0x7/0xb [ 49.440118] ======================= It is because ftrace_modify_code() calls copy_to_user and copy_from_user. These functions have been inserted after guessing that there couldn't be any race condition but copy_[to/from]_user might sleep and __ftrace_update_code is called with local_irq_saved. These function have been inserted since this commit: d5e92e8978fd2574e415dc2792c5eb592978243d: "ftrace: x86 use copy from user function" Signed-off-by: Frederic Weisbecker Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- arch/x86/kernel/ftrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 66d900248fc..222507e8157 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -71,13 +71,13 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, * No real locking needed, this code is run through * kstop_machine, or before SMP starts. */ - if (__copy_from_user(replaced, (char __user *)ip, MCOUNT_INSN_SIZE)) + if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE)) return 1; if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) return 2; - WARN_ON_ONCE(__copy_to_user((char __user *)ip, new_code, + WARN_ON_ONCE(__copy_to_user_inatomic((char __user *)ip, new_code, MCOUNT_INSN_SIZE)); sync_core(); -- 2.11.4.GIT