| Message ID | 20210417023532.354714-1-changbin.du@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: patch: remove lockdep assertion on lock text_mutex | expand |
Ping for review status. This issue makes ftrace hard to use on riscv. On Sat, Apr 17, 2021 at 10:35:32AM +0800, Changbin Du wrote: > The function patch_insn_write() expects that the text_mutex is already > held. There's a case that text_mutex is acquired by ftrace_run_update_code() > under syscall context but then patch_insn_write() will be executed under the > migration kthread context as we involves stop machine. So we should remove > the assertion, or it can cause warning storm in kernel message. > > [ 104.641978] ------------[ cut here ]------------ > [ 104.642327] WARNING: CPU: 0 PID: 13 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x166/0x17c > [ 104.643587] Modules linked in: > [ 104.644691] CPU: 0 PID: 13 Comm: migration/0 Not tainted 5.12.0-rc7-00067-g9cdbf6467424 #102 > [ 104.644907] Hardware name: riscv-virtio,qemu (DT) > [ 104.645068] Stopper: multi_cpu_stop+0x0/0x17e <- 0x0 > [ 104.645349] epc : patch_insn_write+0x166/0x17c > [ 104.645467] ra : patch_insn_write+0x162/0x17c > [ 104.645534] epc : ffffffe0000059c6 ra : ffffffe0000059c2 sp : ffffffe002a33c70 > [ 104.645580] gp : ffffffe0019e5518 tp : ffffffe002a232c0 t0 : ffffffe01295e8a8 > [ 104.645622] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002a33cc0 > [ 104.645675] s1 : ffffffe000007f72 a0 : 0000000000000000 a1 : ffffffffffffffff > [ 104.645716] a2 : 0000000000000001 a3 : 0000000000000000 a4 : 0000000000000001 > [ 104.645757] a5 : ffffffe0799e45c8 a6 : 00000000000ca097 a7 : 0000000000000000 > [ 104.645798] s2 : 0000000000000008 s3 : 0000000000000f72 s4 : ffffffe002a33ce0 > [ 104.645839] s5 : 0000000000000f7a s6 : 0000000000000003 s7 : 0000000000000003 > [ 104.645880] s8 : 0000000000000004 s9 : 0000000000000002 s10: 0000000000000000 > [ 104.645920] s11: 0000000000000002 t3 : 0000000000000001 t4 : ffffffe000c615c8 > [ 104.645958] t5 : 0000000000007fff t6 : 0000000000000380 > [ 104.645998] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 > [ 104.646081] Call Trace: > [ 104.646147] [<ffffffe0000059c6>] patch_insn_write+0x166/0x17c > [ 104.646280] [<ffffffe0000059ec>] patch_text_nosync+0x10/0x32 > [ 104.646317] [<ffffffe000007d0c>] ftrace_update_ftrace_func+0x74/0xac > [ 104.646352] [<ffffffe0000d338a>] ftrace_modify_all_code+0x9c/0x144 > [ 104.646387] [<ffffffe0000d3444>] __ftrace_modify_code+0x12/0x1c > [ 104.646420] [<ffffffe0000c4c2c>] multi_cpu_stop+0xa8/0x17e > [ 104.646451] [<ffffffe0000c4474>] cpu_stopper_thread+0xb2/0x156 > [ 104.646489] [<ffffffe00003645e>] smpboot_thread_fn+0x102/0x1ea > [ 104.646524] [<ffffffe0000311b0>] kthread+0x132/0x148 > [ 104.646556] [<ffffffe000002e02>] ret_from_exception+0x0/0x14 > [ 104.646657] ---[ end trace ccf71babb9de4d5b ]--- > [ 104.647444] ------------[ cut here ]------------ > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > --- > arch/riscv/kernel/patch.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > index 0b552873a577..6d2ed9c15065 100644 > --- a/arch/riscv/kernel/patch.c > +++ b/arch/riscv/kernel/patch.c > @@ -49,19 +49,18 @@ static void patch_unmap(int fixmap) > } > NOKPROBE_SYMBOL(patch_unmap); > > + > +/* > + * Before reaching here, it was expected to lock the text_mutex > + * already, so we don't need to give another lock here and could > + * ensure that it was safe between each cores. > + */ > static int patch_insn_write(void *addr, const void *insn, size_t len) > { > void *waddr = addr; > bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > int ret; > > - /* > - * Before reaching here, it was expected to lock the text_mutex > - * already, so we don't need to give another lock here and could > - * ensure that it was safe between each cores. > - */ > - lockdep_assert_held(&text_mutex); > - > if (across_pages) > patch_map(addr + len, FIX_TEXT_POKE1); > > -- > 2.27.0 >
On Fri, 16 Apr 2021 19:35:32 PDT (-0700), changbin.du@gmail.com wrote: > The function patch_insn_write() expects that the text_mutex is already > held. There's a case that text_mutex is acquired by ftrace_run_update_code() > under syscall context but then patch_insn_write() will be executed under the > migration kthread context as we involves stop machine. So we should remove > the assertion, or it can cause warning storm in kernel message. > > [ 104.641978] ------------[ cut here ]------------ > [ 104.642327] WARNING: CPU: 0 PID: 13 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x166/0x17c > [ 104.643587] Modules linked in: > [ 104.644691] CPU: 0 PID: 13 Comm: migration/0 Not tainted 5.12.0-rc7-00067-g9cdbf6467424 #102 > [ 104.644907] Hardware name: riscv-virtio,qemu (DT) > [ 104.645068] Stopper: multi_cpu_stop+0x0/0x17e <- 0x0 > [ 104.645349] epc : patch_insn_write+0x166/0x17c > [ 104.645467] ra : patch_insn_write+0x162/0x17c > [ 104.645534] epc : ffffffe0000059c6 ra : ffffffe0000059c2 sp : ffffffe002a33c70 > [ 104.645580] gp : ffffffe0019e5518 tp : ffffffe002a232c0 t0 : ffffffe01295e8a8 > [ 104.645622] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002a33cc0 > [ 104.645675] s1 : ffffffe000007f72 a0 : 0000000000000000 a1 : ffffffffffffffff > [ 104.645716] a2 : 0000000000000001 a3 : 0000000000000000 a4 : 0000000000000001 > [ 104.645757] a5 : ffffffe0799e45c8 a6 : 00000000000ca097 a7 : 0000000000000000 > [ 104.645798] s2 : 0000000000000008 s3 : 0000000000000f72 s4 : ffffffe002a33ce0 > [ 104.645839] s5 : 0000000000000f7a s6 : 0000000000000003 s7 : 0000000000000003 > [ 104.645880] s8 : 0000000000000004 s9 : 0000000000000002 s10: 0000000000000000 > [ 104.645920] s11: 0000000000000002 t3 : 0000000000000001 t4 : ffffffe000c615c8 > [ 104.645958] t5 : 0000000000007fff t6 : 0000000000000380 > [ 104.645998] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 > [ 104.646081] Call Trace: > [ 104.646147] [<ffffffe0000059c6>] patch_insn_write+0x166/0x17c > [ 104.646280] [<ffffffe0000059ec>] patch_text_nosync+0x10/0x32 > [ 104.646317] [<ffffffe000007d0c>] ftrace_update_ftrace_func+0x74/0xac > [ 104.646352] [<ffffffe0000d338a>] ftrace_modify_all_code+0x9c/0x144 > [ 104.646387] [<ffffffe0000d3444>] __ftrace_modify_code+0x12/0x1c > [ 104.646420] [<ffffffe0000c4c2c>] multi_cpu_stop+0xa8/0x17e > [ 104.646451] [<ffffffe0000c4474>] cpu_stopper_thread+0xb2/0x156 > [ 104.646489] [<ffffffe00003645e>] smpboot_thread_fn+0x102/0x1ea > [ 104.646524] [<ffffffe0000311b0>] kthread+0x132/0x148 > [ 104.646556] [<ffffffe000002e02>] ret_from_exception+0x0/0x14 > [ 104.646657] ---[ end trace ccf71babb9de4d5b ]--- > [ 104.647444] ------------[ cut here ]------------ > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > --- > arch/riscv/kernel/patch.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > index 0b552873a577..6d2ed9c15065 100644 > --- a/arch/riscv/kernel/patch.c > +++ b/arch/riscv/kernel/patch.c > @@ -49,19 +49,18 @@ static void patch_unmap(int fixmap) > } > NOKPROBE_SYMBOL(patch_unmap); > > + > +/* > + * Before reaching here, it was expected to lock the text_mutex > + * already, so we don't need to give another lock here and could > + * ensure that it was safe between each cores. > + */ > static int patch_insn_write(void *addr, const void *insn, size_t len) > { > void *waddr = addr; > bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > int ret; > > - /* > - * Before reaching here, it was expected to lock the text_mutex > - * already, so we don't need to give another lock here and could > - * ensure that it was safe between each cores. > - */ > - lockdep_assert_held(&text_mutex); > - > if (across_pages) > patch_map(addr + len, FIX_TEXT_POKE1); Well, we definately need the lock -- otherwise concurrent callers will install conflicting maps for FIX_TEXT_POKE*, step on each other, and install the wrong patch. I just sent out a patch to use an explicit lock here, as sharing text_mutex doesn't seem safe.
On Wed, Apr 28, 2021 at 11:20:20PM -0700, Palmer Dabbelt wrote: > On Fri, 16 Apr 2021 19:35:32 PDT (-0700), changbin.du@gmail.com wrote: > > The function patch_insn_write() expects that the text_mutex is already > > held. There's a case that text_mutex is acquired by ftrace_run_update_code() > > under syscall context but then patch_insn_write() will be executed under the > > migration kthread context as we involves stop machine. So we should remove > > the assertion, or it can cause warning storm in kernel message. > > > > [ 104.641978] ------------[ cut here ]------------ > > [ 104.642327] WARNING: CPU: 0 PID: 13 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x166/0x17c > > [ 104.643587] Modules linked in: > > [ 104.644691] CPU: 0 PID: 13 Comm: migration/0 Not tainted 5.12.0-rc7-00067-g9cdbf6467424 #102 > > [ 104.644907] Hardware name: riscv-virtio,qemu (DT) > > [ 104.645068] Stopper: multi_cpu_stop+0x0/0x17e <- 0x0 > > [ 104.645349] epc : patch_insn_write+0x166/0x17c > > [ 104.645467] ra : patch_insn_write+0x162/0x17c > > [ 104.645534] epc : ffffffe0000059c6 ra : ffffffe0000059c2 sp : ffffffe002a33c70 > > [ 104.645580] gp : ffffffe0019e5518 tp : ffffffe002a232c0 t0 : ffffffe01295e8a8 > > [ 104.645622] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002a33cc0 > > [ 104.645675] s1 : ffffffe000007f72 a0 : 0000000000000000 a1 : ffffffffffffffff > > [ 104.645716] a2 : 0000000000000001 a3 : 0000000000000000 a4 : 0000000000000001 > > [ 104.645757] a5 : ffffffe0799e45c8 a6 : 00000000000ca097 a7 : 0000000000000000 > > [ 104.645798] s2 : 0000000000000008 s3 : 0000000000000f72 s4 : ffffffe002a33ce0 > > [ 104.645839] s5 : 0000000000000f7a s6 : 0000000000000003 s7 : 0000000000000003 > > [ 104.645880] s8 : 0000000000000004 s9 : 0000000000000002 s10: 0000000000000000 > > [ 104.645920] s11: 0000000000000002 t3 : 0000000000000001 t4 : ffffffe000c615c8 > > [ 104.645958] t5 : 0000000000007fff t6 : 0000000000000380 > > [ 104.645998] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 > > [ 104.646081] Call Trace: > > [ 104.646147] [<ffffffe0000059c6>] patch_insn_write+0x166/0x17c > > [ 104.646280] [<ffffffe0000059ec>] patch_text_nosync+0x10/0x32 > > [ 104.646317] [<ffffffe000007d0c>] ftrace_update_ftrace_func+0x74/0xac > > [ 104.646352] [<ffffffe0000d338a>] ftrace_modify_all_code+0x9c/0x144 > > [ 104.646387] [<ffffffe0000d3444>] __ftrace_modify_code+0x12/0x1c > > [ 104.646420] [<ffffffe0000c4c2c>] multi_cpu_stop+0xa8/0x17e > > [ 104.646451] [<ffffffe0000c4474>] cpu_stopper_thread+0xb2/0x156 > > [ 104.646489] [<ffffffe00003645e>] smpboot_thread_fn+0x102/0x1ea > > [ 104.646524] [<ffffffe0000311b0>] kthread+0x132/0x148 > > [ 104.646556] [<ffffffe000002e02>] ret_from_exception+0x0/0x14 > > [ 104.646657] ---[ end trace ccf71babb9de4d5b ]--- > > [ 104.647444] ------------[ cut here ]------------ > > > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > --- > > arch/riscv/kernel/patch.c | 13 ++++++------- > > 1 file changed, 6 insertions(+), 7 deletions(-) > > > > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > > index 0b552873a577..6d2ed9c15065 100644 > > --- a/arch/riscv/kernel/patch.c > > +++ b/arch/riscv/kernel/patch.c > > @@ -49,19 +49,18 @@ static void patch_unmap(int fixmap) > > } > > NOKPROBE_SYMBOL(patch_unmap); > > > > + > > +/* > > + * Before reaching here, it was expected to lock the text_mutex > > + * already, so we don't need to give another lock here and could > > + * ensure that it was safe between each cores. > > + */ > > static int patch_insn_write(void *addr, const void *insn, size_t len) > > { > > void *waddr = addr; > > bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > > int ret; > > > > - /* > > - * Before reaching here, it was expected to lock the text_mutex > > - * already, so we don't need to give another lock here and could > > - * ensure that it was safe between each cores. > > - */ > > - lockdep_assert_held(&text_mutex); > > - > > if (across_pages) > > patch_map(addr + len, FIX_TEXT_POKE1); > > Well, we definately need the lock -- otherwise concurrent callers will > install conflicting maps for FIX_TEXT_POKE*, step on each other, and install > the wrong patch. I just sent out a patch to use an explicit lock here, as > sharing text_mutex doesn't seem safe. It has already locked by text_mutex. The real problem is lockdep cannot handle this case(with stopmachine) or it is a false positive report.
On Wed, Apr 28, 2021 at 11:20:20PM -0700, Palmer Dabbelt wrote: > On Fri, 16 Apr 2021 19:35:32 PDT (-0700), changbin.du@gmail.com wrote: > > The function patch_insn_write() expects that the text_mutex is already > > held. There's a case that text_mutex is acquired by ftrace_run_update_code() > > under syscall context but then patch_insn_write() will be executed under the > > migration kthread context as we involves stop machine. So we should remove > > the assertion, or it can cause warning storm in kernel message. > > > > [ 104.641978] ------------[ cut here ]------------ > > [ 104.642327] WARNING: CPU: 0 PID: 13 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x166/0x17c > > [ 104.643587] Modules linked in: > > [ 104.644691] CPU: 0 PID: 13 Comm: migration/0 Not tainted 5.12.0-rc7-00067-g9cdbf6467424 #102 > > [ 104.644907] Hardware name: riscv-virtio,qemu (DT) > > [ 104.645068] Stopper: multi_cpu_stop+0x0/0x17e <- 0x0 > > [ 104.645349] epc : patch_insn_write+0x166/0x17c > > [ 104.645467] ra : patch_insn_write+0x162/0x17c > > [ 104.645534] epc : ffffffe0000059c6 ra : ffffffe0000059c2 sp : ffffffe002a33c70 > > [ 104.645580] gp : ffffffe0019e5518 tp : ffffffe002a232c0 t0 : ffffffe01295e8a8 > > [ 104.645622] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002a33cc0 > > [ 104.645675] s1 : ffffffe000007f72 a0 : 0000000000000000 a1 : ffffffffffffffff > > [ 104.645716] a2 : 0000000000000001 a3 : 0000000000000000 a4 : 0000000000000001 > > [ 104.645757] a5 : ffffffe0799e45c8 a6 : 00000000000ca097 a7 : 0000000000000000 > > [ 104.645798] s2 : 0000000000000008 s3 : 0000000000000f72 s4 : ffffffe002a33ce0 > > [ 104.645839] s5 : 0000000000000f7a s6 : 0000000000000003 s7 : 0000000000000003 > > [ 104.645880] s8 : 0000000000000004 s9 : 0000000000000002 s10: 0000000000000000 > > [ 104.645920] s11: 0000000000000002 t3 : 0000000000000001 t4 : ffffffe000c615c8 > > [ 104.645958] t5 : 0000000000007fff t6 : 0000000000000380 > > [ 104.645998] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 > > [ 104.646081] Call Trace: > > [ 104.646147] [<ffffffe0000059c6>] patch_insn_write+0x166/0x17c > > [ 104.646280] [<ffffffe0000059ec>] patch_text_nosync+0x10/0x32 > > [ 104.646317] [<ffffffe000007d0c>] ftrace_update_ftrace_func+0x74/0xac > > [ 104.646352] [<ffffffe0000d338a>] ftrace_modify_all_code+0x9c/0x144 > > [ 104.646387] [<ffffffe0000d3444>] __ftrace_modify_code+0x12/0x1c > > [ 104.646420] [<ffffffe0000c4c2c>] multi_cpu_stop+0xa8/0x17e > > [ 104.646451] [<ffffffe0000c4474>] cpu_stopper_thread+0xb2/0x156 > > [ 104.646489] [<ffffffe00003645e>] smpboot_thread_fn+0x102/0x1ea > > [ 104.646524] [<ffffffe0000311b0>] kthread+0x132/0x148 > > [ 104.646556] [<ffffffe000002e02>] ret_from_exception+0x0/0x14 > > [ 104.646657] ---[ end trace ccf71babb9de4d5b ]--- > > [ 104.647444] ------------[ cut here ]------------ > > > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > --- > > arch/riscv/kernel/patch.c | 13 ++++++------- > > 1 file changed, 6 insertions(+), 7 deletions(-) > > > > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > > index 0b552873a577..6d2ed9c15065 100644 > > --- a/arch/riscv/kernel/patch.c > > +++ b/arch/riscv/kernel/patch.c > > @@ -49,19 +49,18 @@ static void patch_unmap(int fixmap) > > } > > NOKPROBE_SYMBOL(patch_unmap); > > > > + > > +/* > > + * Before reaching here, it was expected to lock the text_mutex > > + * already, so we don't need to give another lock here and could > > + * ensure that it was safe between each cores. > > + */ > > static int patch_insn_write(void *addr, const void *insn, size_t len) > > { > > void *waddr = addr; > > bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > > int ret; > > > > - /* > > - * Before reaching here, it was expected to lock the text_mutex > > - * already, so we don't need to give another lock here and could > > - * ensure that it was safe between each cores. > > - */ > > - lockdep_assert_held(&text_mutex); > > - > > if (across_pages) > > patch_map(addr + len, FIX_TEXT_POKE1); > > Well, we definately need the lock -- otherwise concurrent callers will > install conflicting maps for FIX_TEXT_POKE*, step on each other, and install > the wrong patch. I just sent out a patch to use an explicit lock here, as > sharing text_mutex doesn't seem safe. Just a note that this issue still exist on mainline.
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 0b552873a577..6d2ed9c15065 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -49,19 +49,18 @@ static void patch_unmap(int fixmap) } NOKPROBE_SYMBOL(patch_unmap); + +/* + * Before reaching here, it was expected to lock the text_mutex + * already, so we don't need to give another lock here and could + * ensure that it was safe between each cores. + */ static int patch_insn_write(void *addr, const void *insn, size_t len) { void *waddr = addr; bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; int ret; - /* - * Before reaching here, it was expected to lock the text_mutex - * already, so we don't need to give another lock here and could - * ensure that it was safe between each cores. - */ - lockdep_assert_held(&text_mutex); - if (across_pages) patch_map(addr + len, FIX_TEXT_POKE1);
The function patch_insn_write() expects that the text_mutex is already held. There's a case that text_mutex is acquired by ftrace_run_update_code() under syscall context but then patch_insn_write() will be executed under the migration kthread context as we involves stop machine. So we should remove the assertion, or it can cause warning storm in kernel message. [ 104.641978] ------------[ cut here ]------------ [ 104.642327] WARNING: CPU: 0 PID: 13 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x166/0x17c [ 104.643587] Modules linked in: [ 104.644691] CPU: 0 PID: 13 Comm: migration/0 Not tainted 5.12.0-rc7-00067-g9cdbf6467424 #102 [ 104.644907] Hardware name: riscv-virtio,qemu (DT) [ 104.645068] Stopper: multi_cpu_stop+0x0/0x17e <- 0x0 [ 104.645349] epc : patch_insn_write+0x166/0x17c [ 104.645467] ra : patch_insn_write+0x162/0x17c [ 104.645534] epc : ffffffe0000059c6 ra : ffffffe0000059c2 sp : ffffffe002a33c70 [ 104.645580] gp : ffffffe0019e5518 tp : ffffffe002a232c0 t0 : ffffffe01295e8a8 [ 104.645622] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002a33cc0 [ 104.645675] s1 : ffffffe000007f72 a0 : 0000000000000000 a1 : ffffffffffffffff [ 104.645716] a2 : 0000000000000001 a3 : 0000000000000000 a4 : 0000000000000001 [ 104.645757] a5 : ffffffe0799e45c8 a6 : 00000000000ca097 a7 : 0000000000000000 [ 104.645798] s2 : 0000000000000008 s3 : 0000000000000f72 s4 : ffffffe002a33ce0 [ 104.645839] s5 : 0000000000000f7a s6 : 0000000000000003 s7 : 0000000000000003 [ 104.645880] s8 : 0000000000000004 s9 : 0000000000000002 s10: 0000000000000000 [ 104.645920] s11: 0000000000000002 t3 : 0000000000000001 t4 : ffffffe000c615c8 [ 104.645958] t5 : 0000000000007fff t6 : 0000000000000380 [ 104.645998] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 [ 104.646081] Call Trace: [ 104.646147] [<ffffffe0000059c6>] patch_insn_write+0x166/0x17c [ 104.646280] [<ffffffe0000059ec>] patch_text_nosync+0x10/0x32 [ 104.646317] [<ffffffe000007d0c>] ftrace_update_ftrace_func+0x74/0xac [ 104.646352] [<ffffffe0000d338a>] ftrace_modify_all_code+0x9c/0x144 [ 104.646387] [<ffffffe0000d3444>] __ftrace_modify_code+0x12/0x1c [ 104.646420] [<ffffffe0000c4c2c>] multi_cpu_stop+0xa8/0x17e [ 104.646451] [<ffffffe0000c4474>] cpu_stopper_thread+0xb2/0x156 [ 104.646489] [<ffffffe00003645e>] smpboot_thread_fn+0x102/0x1ea [ 104.646524] [<ffffffe0000311b0>] kthread+0x132/0x148 [ 104.646556] [<ffffffe000002e02>] ret_from_exception+0x0/0x14 [ 104.646657] ---[ end trace ccf71babb9de4d5b ]--- [ 104.647444] ------------[ cut here ]------------ Signed-off-by: Changbin Du <changbin.du@gmail.com> --- arch/riscv/kernel/patch.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)