| Message ID | 1637576257-11590-1-git-send-email-yangtiezhu@loongson.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | MIPS: Fix using smp_processor_id() in preemptible in show_cpuinfo() | expand |
On Mon, Nov 22, 2021 at 06:17:37PM +0800, Tiezhu Yang wrote: > There exists the following issue under DEBUG_PREEMPT: > > BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1 > caller is show_cpuinfo+0x460/0xea0 > ... > Call Trace: > [<ffffffff8020f0dc>] show_stack+0x94/0x128 > [<ffffffff80e6cab4>] dump_stack_lvl+0x94/0xd8 > [<ffffffff80e74c5c>] check_preemption_disabled+0x104/0x110 > [<ffffffff802209c8>] show_cpuinfo+0x460/0xea0 > [<ffffffff80539d54>] seq_read_iter+0xfc/0x4f8 > [<ffffffff804fcc10>] new_sync_read+0x110/0x1b8 > [<ffffffff804ff57c>] vfs_read+0x1b4/0x1d0 > [<ffffffff804ffb18>] ksys_read+0xd0/0x110 > [<ffffffff8021c090>] syscall_common+0x34/0x58 > > We can see the following call trace: > show_cpuinfo() > cpu_has_fpu > current_cpu_data > smp_processor_id() > > $ addr2line -f -e vmlinux 0xffffffff802209c8 > show_cpuinfo > arch/mips/kernel/proc.c:188 > > $ head -188 arch/mips/kernel/proc.c | tail -1 > if (cpu_has_fpu) > > arch/mips/include/asm/cpu-features.h > # define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU) > > arch/mips/include/asm/cpu-info.h > #define current_cpu_data cpu_data[smp_processor_id()] > > Based on the above analysis, fix the issue by disabling preemption > around cpu_has_fpu in show_cpuinfo(). > > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> missing Fixes: 626bfa037299 ("MIPS: kernel: proc: add CPU option reporting") > --- > arch/mips/kernel/proc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c > index 376a6e2..c6c2661 100644 > --- a/arch/mips/kernel/proc.c > +++ b/arch/mips/kernel/proc.c > @@ -185,8 +185,10 @@ static int show_cpuinfo(struct seq_file *m, void *v) > seq_puts(m, " tx39_cache"); > if (cpu_has_octeon_cache) > seq_puts(m, " octeon_cache"); > + preempt_disable(); > if (cpu_has_fpu) > seq_puts(m, " fpu"); > + preempt_enable(); what about using raw_cpu_has_fpu() instead ? Thomas.
On 11/25/2021 05:34 PM, Thomas Bogendoerfer wrote: > On Mon, Nov 22, 2021 at 06:17:37PM +0800, Tiezhu Yang wrote: >> There exists the following issue under DEBUG_PREEMPT: >> >> BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1 >> caller is show_cpuinfo+0x460/0xea0 >> ... >> Call Trace: >> [<ffffffff8020f0dc>] show_stack+0x94/0x128 >> [<ffffffff80e6cab4>] dump_stack_lvl+0x94/0xd8 >> [<ffffffff80e74c5c>] check_preemption_disabled+0x104/0x110 >> [<ffffffff802209c8>] show_cpuinfo+0x460/0xea0 >> [<ffffffff80539d54>] seq_read_iter+0xfc/0x4f8 >> [<ffffffff804fcc10>] new_sync_read+0x110/0x1b8 >> [<ffffffff804ff57c>] vfs_read+0x1b4/0x1d0 >> [<ffffffff804ffb18>] ksys_read+0xd0/0x110 >> [<ffffffff8021c090>] syscall_common+0x34/0x58 >> >> We can see the following call trace: >> show_cpuinfo() >> cpu_has_fpu >> current_cpu_data >> smp_processor_id() >> >> $ addr2line -f -e vmlinux 0xffffffff802209c8 >> show_cpuinfo >> arch/mips/kernel/proc.c:188 >> >> $ head -188 arch/mips/kernel/proc.c | tail -1 >> if (cpu_has_fpu) >> >> arch/mips/include/asm/cpu-features.h >> # define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU) >> >> arch/mips/include/asm/cpu-info.h >> #define current_cpu_data cpu_data[smp_processor_id()] >> >> Based on the above analysis, fix the issue by disabling preemption >> around cpu_has_fpu in show_cpuinfo(). >> >> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> > > missing > > Fixes: 626bfa037299 ("MIPS: kernel: proc: add CPU option reporting") Thank you, will add in v2. > >> --- >> arch/mips/kernel/proc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c >> index 376a6e2..c6c2661 100644 >> --- a/arch/mips/kernel/proc.c >> +++ b/arch/mips/kernel/proc.c >> @@ -185,8 +185,10 @@ static int show_cpuinfo(struct seq_file *m, void *v) >> seq_puts(m, " tx39_cache"); >> if (cpu_has_octeon_cache) >> seq_puts(m, " octeon_cache"); >> + preempt_disable(); >> if (cpu_has_fpu) >> seq_puts(m, " fpu"); >> + preempt_enable(); > > what about using raw_cpu_has_fpu() instead ? OK, no problem, using raw_cpu_has_fpu can also fix the issue and looks better, I will send v2 soon. Thanks, Tiezhu > > Thomas. >
diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c index 376a6e2..c6c2661 100644 --- a/arch/mips/kernel/proc.c +++ b/arch/mips/kernel/proc.c @@ -185,8 +185,10 @@ static int show_cpuinfo(struct seq_file *m, void *v) seq_puts(m, " tx39_cache"); if (cpu_has_octeon_cache) seq_puts(m, " octeon_cache"); + preempt_disable(); if (cpu_has_fpu) seq_puts(m, " fpu"); + preempt_enable(); if (cpu_has_32fpr) seq_puts(m, " 32fpr"); if (cpu_has_cache_cdex_p)
There exists the following issue under DEBUG_PREEMPT: BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1 caller is show_cpuinfo+0x460/0xea0 ... Call Trace: [<ffffffff8020f0dc>] show_stack+0x94/0x128 [<ffffffff80e6cab4>] dump_stack_lvl+0x94/0xd8 [<ffffffff80e74c5c>] check_preemption_disabled+0x104/0x110 [<ffffffff802209c8>] show_cpuinfo+0x460/0xea0 [<ffffffff80539d54>] seq_read_iter+0xfc/0x4f8 [<ffffffff804fcc10>] new_sync_read+0x110/0x1b8 [<ffffffff804ff57c>] vfs_read+0x1b4/0x1d0 [<ffffffff804ffb18>] ksys_read+0xd0/0x110 [<ffffffff8021c090>] syscall_common+0x34/0x58 We can see the following call trace: show_cpuinfo() cpu_has_fpu current_cpu_data smp_processor_id() $ addr2line -f -e vmlinux 0xffffffff802209c8 show_cpuinfo arch/mips/kernel/proc.c:188 $ head -188 arch/mips/kernel/proc.c | tail -1 if (cpu_has_fpu) arch/mips/include/asm/cpu-features.h # define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU) arch/mips/include/asm/cpu-info.h #define current_cpu_data cpu_data[smp_processor_id()] Based on the above analysis, fix the issue by disabling preemption around cpu_has_fpu in show_cpuinfo(). Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> --- arch/mips/kernel/proc.c | 2 ++ 1 file changed, 2 insertions(+)