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| Started by | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| First post | 2017-08-14 09:30 +0200 |
| Last post | 2017-08-15 13:10 +0200 |
| Articles | 3 — 3 participants |
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Re: Regression in kernel 4.13-rcX for 32-bit x86 system - bisected to commit fc8dffd379ca Thomas Gleixner <tglx@linutronix.de> - 2017-08-14 09:30 +0200
Re: Regression in kernel 4.13-rcX for 32-bit x86 system - bisected to commit fc8dffd379ca Larry Finger <Larry.Finger@lwfinger.net> - 2017-08-14 21:50 +0200
[tip:x86/urgent] x86/mtrr: Prevent CPU hotplug lock recursion tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-08-15 13:10 +0200
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-08-14 09:30 +0200 |
| Subject | Re: Regression in kernel 4.13-rcX for 32-bit x86 system - bisected to commit fc8dffd379ca |
| Message-ID | <uehZ0-1bj-21@gated-at.bofh.it> |
On Mon, 14 Aug 2017, Larry Finger wrote:
> My Del Latitude D600 (single 32-bit CPU) shows the following locking message
> when booted:
>
> ============================================
> WARNING: possible recursive locking detected
> 4.12.0-rc2-00029-gfc8dffd #159 Not tainted
> --------------------------------------------
> systemd-udevd/153 is trying to acquire lock:
> (cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c030fc26>] stop_machine+0x16/0x30
>
> but task is already holding lock:
> (cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c0234353>] mtrr_add_page+0x83/0x470
....
> cpus_read_lock+0x48/0x90
> ? stop_machine+0x16/0x30
> stop_machine+0x16/0x30
> mtrr_add_page+0x18b/0x470
> mtrr_add+0x3e/0x70
> This problem was bisected to commit fc8dffd379ca ("cpu/hotplug: Convert
> hotplug locking to percpu rwsem"). I am very confident in the correctness of
> the bisection.
Fix below.
Thanks,
tglx
8<--------------------
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index c5bb63be4ba1..40d5a8a75212 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -237,6 +237,18 @@ set_mtrr(unsigned int reg, unsigned long base, unsigned long size, mtrr_type typ
stop_machine(mtrr_rendezvous_handler, &data, cpu_online_mask);
}
+static void set_mtrr_cpuslocked(unsigned int reg, unsigned long base,
+ unsigned long size, mtrr_type type)
+{
+ struct set_mtrr_data data = { .smp_reg = reg,
+ .smp_base = base,
+ .smp_size = size,
+ .smp_type = type
+ };
+
+ stop_machine_cpuslocked(mtrr_rendezvous_handler, &data, cpu_online_mask);
+}
+
static void set_mtrr_from_inactive_cpu(unsigned int reg, unsigned long base,
unsigned long size, mtrr_type type)
{
@@ -370,7 +382,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
/* Search for an empty MTRR */
i = mtrr_if->get_free_region(base, size, replace);
if (i >= 0) {
- set_mtrr(i, base, size, type);
+ set_mtrr_cpuslocked(i, base, size, type);
if (likely(replace < 0)) {
mtrr_usage_table[i] = 1;
} else {
@@ -378,7 +390,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
if (increment)
mtrr_usage_table[i]++;
if (unlikely(replace != i)) {
- set_mtrr(replace, 0, 0, 0);
+ set_mtrr_cpuslocked(replace, 0, 0, 0);
mtrr_usage_table[replace] = 0;
}
}
@@ -506,7 +518,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
goto out;
}
if (--mtrr_usage_table[reg] < 1)
- set_mtrr(reg, 0, 0, 0);
+ set_mtrr_cpuslocked(reg, 0, 0, 0);
error = reg;
out:
mutex_unlock(&mtrr_mutex);
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| From | Larry Finger <Larry.Finger@lwfinger.net> |
|---|---|
| Date | 2017-08-14 21:50 +0200 |
| Subject | Re: Regression in kernel 4.13-rcX for 32-bit x86 system - bisected to commit fc8dffd379ca |
| Message-ID | <uetx8-8g9-7@gated-at.bofh.it> |
| In reply to | #1710685 |
On 08/14/2017 02:21 AM, Thomas Gleixner wrote:
> On Mon, 14 Aug 2017, Larry Finger wrote:
>
>> My Del Latitude D600 (single 32-bit CPU) shows the following locking message
>> when booted:
>>
>> ============================================
>> WARNING: possible recursive locking detected
>> 4.12.0-rc2-00029-gfc8dffd #159 Not tainted
>> --------------------------------------------
>> systemd-udevd/153 is trying to acquire lock:
>> (cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c030fc26>] stop_machine+0x16/0x30
>>
>> but task is already holding lock:
>> (cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c0234353>] mtrr_add_page+0x83/0x470
>
> ....
>
>> cpus_read_lock+0x48/0x90
>> ? stop_machine+0x16/0x30
>> stop_machine+0x16/0x30
>> mtrr_add_page+0x18b/0x470
>> mtrr_add+0x3e/0x70
>
>> This problem was bisected to commit fc8dffd379ca ("cpu/hotplug: Convert
>> hotplug locking to percpu rwsem"). I am very confident in the correctness of
>> the bisection.
>
> Fix below.
>
> Thanks,
>
> tglx
>
> 8<--------------------
>
> diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
> index c5bb63be4ba1..40d5a8a75212 100644
> --- a/arch/x86/kernel/cpu/mtrr/main.c
> +++ b/arch/x86/kernel/cpu/mtrr/main.c
> @@ -237,6 +237,18 @@ set_mtrr(unsigned int reg, unsigned long base, unsigned long size, mtrr_type typ
> stop_machine(mtrr_rendezvous_handler, &data, cpu_online_mask);
> }
>
> +static void set_mtrr_cpuslocked(unsigned int reg, unsigned long base,
> + unsigned long size, mtrr_type type)
> +{
> + struct set_mtrr_data data = { .smp_reg = reg,
> + .smp_base = base,
> + .smp_size = size,
> + .smp_type = type
> + };
> +
> + stop_machine_cpuslocked(mtrr_rendezvous_handler, &data, cpu_online_mask);
> +}
> +
> static void set_mtrr_from_inactive_cpu(unsigned int reg, unsigned long base,
> unsigned long size, mtrr_type type)
> {
> @@ -370,7 +382,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
> /* Search for an empty MTRR */
> i = mtrr_if->get_free_region(base, size, replace);
> if (i >= 0) {
> - set_mtrr(i, base, size, type);
> + set_mtrr_cpuslocked(i, base, size, type);
> if (likely(replace < 0)) {
> mtrr_usage_table[i] = 1;
> } else {
> @@ -378,7 +390,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
> if (increment)
> mtrr_usage_table[i]++;
> if (unlikely(replace != i)) {
> - set_mtrr(replace, 0, 0, 0);
> + set_mtrr_cpuslocked(replace, 0, 0, 0);
> mtrr_usage_table[replace] = 0;
> }
> }
> @@ -506,7 +518,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
> goto out;
> }
> if (--mtrr_usage_table[reg] < 1)
> - set_mtrr(reg, 0, 0, 0);
> + set_mtrr_cpuslocked(reg, 0, 0, 0);
> error = reg;
> out:
> mutex_unlock(&mtrr_mutex);
>
That fix works for me.
Thanks,
Larry
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| From | tip-bot for Thomas Gleixner <tipbot@zytor.com> |
|---|---|
| Date | 2017-08-15 13:10 +0200 |
| Subject | [tip:x86/urgent] x86/mtrr: Prevent CPU hotplug lock recursion |
| Message-ID | <ueHTr-xi-3@gated-at.bofh.it> |
| In reply to | #1710685 |
Commit-ID: 84393817db09bb436e934f8f8cc981cbca9ea4dc
Gitweb: http://git.kernel.org/tip/84393817db09bb436e934f8f8cc981cbca9ea4dc
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 15 Aug 2017 13:03:47 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 15 Aug 2017 13:03:47 +0200
x86/mtrr: Prevent CPU hotplug lock recursion
Larry reported a CPU hotplug lock recursion in the MTRR code.
============================================
WARNING: possible recursive locking detected
systemd-udevd/153 is trying to acquire lock:
(cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c030fc26>] stop_machine+0x16/0x30
but task is already holding lock:
(cpu_hotplug_lock.rw_sem){.+.+.+}, at: [<c0234353>] mtrr_add_page+0x83/0x470
....
cpus_read_lock+0x48/0x90
stop_machine+0x16/0x30
mtrr_add_page+0x18b/0x470
mtrr_add+0x3e/0x70
mtrr_add_page() holds the hotplug rwsem already and calls stop_machine()
which acquires it again.
Call stop_machine_cpuslocked() instead.
Reported-and-tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1708140920250.1865@nanos
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/cpu/mtrr/main.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index c5bb63b..40d5a8a 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -237,6 +237,18 @@ set_mtrr(unsigned int reg, unsigned long base, unsigned long size, mtrr_type typ
stop_machine(mtrr_rendezvous_handler, &data, cpu_online_mask);
}
+static void set_mtrr_cpuslocked(unsigned int reg, unsigned long base,
+ unsigned long size, mtrr_type type)
+{
+ struct set_mtrr_data data = { .smp_reg = reg,
+ .smp_base = base,
+ .smp_size = size,
+ .smp_type = type
+ };
+
+ stop_machine_cpuslocked(mtrr_rendezvous_handler, &data, cpu_online_mask);
+}
+
static void set_mtrr_from_inactive_cpu(unsigned int reg, unsigned long base,
unsigned long size, mtrr_type type)
{
@@ -370,7 +382,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
/* Search for an empty MTRR */
i = mtrr_if->get_free_region(base, size, replace);
if (i >= 0) {
- set_mtrr(i, base, size, type);
+ set_mtrr_cpuslocked(i, base, size, type);
if (likely(replace < 0)) {
mtrr_usage_table[i] = 1;
} else {
@@ -378,7 +390,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
if (increment)
mtrr_usage_table[i]++;
if (unlikely(replace != i)) {
- set_mtrr(replace, 0, 0, 0);
+ set_mtrr_cpuslocked(replace, 0, 0, 0);
mtrr_usage_table[replace] = 0;
}
}
@@ -506,7 +518,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
goto out;
}
if (--mtrr_usage_table[reg] < 1)
- set_mtrr(reg, 0, 0, 0);
+ set_mtrr_cpuslocked(reg, 0, 0, 0);
error = reg;
out:
mutex_unlock(&mtrr_mutex);
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