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authorThomas Gleixner <tglx@linutronix.de>2017-08-15 13:03:47 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-08-15 13:03:47 +0200
commit84393817db09bb436e934f8f8cc981cbca9ea4dc (patch)
tree90759da335f746a81f1019271bfb75370dc38314 /arch/x86/kernel/cpu
parentb45e4c45b13275a6b4a3f83ae8301a1963fbe5d0 (diff)
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>
Diffstat (limited to 'arch/x86/kernel/cpu')
-rw-r--r--arch/x86/kernel/cpu/mtrr/main.c18
1 files changed, 15 insertions, 3 deletions
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);