Subject: + sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs.patch added to -mm tree
To: riel@xxxxxxxxxx,cxie@xxxxxxxxxx,paulmck@xxxxxxxxxxxxxxxxxx,rdunlap@xxxxxxxxxxxxx,richard@xxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 29 Apr 2014 16:25:31 -0700
The patch titled
Subject: sysrq,rcu: suppress RCU stall warnings while sysrq runs
has been added to the -mm tree. Its filename is
sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs.patch
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------------------------------------------------------
From: Rik van Riel <riel@xxxxxxxxxx>
Subject: sysrq,rcu: suppress RCU stall warnings while sysrq runs
Some sysrq handlers can run for a long time, because they dump a lot of
data onto a serial console. Having RCU stall warnings pop up in the
middle of them only makes the problem worse.
This patch temporarily disables RCU stall warnings while a sysrq request
is handled.
[paulmck@xxxxxxxxxxxxxxxxxx: fix TINY_RCU build error]
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Suggested-by: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Madper Xie <cxie@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/tty/sysrq.c | 3 +++
include/linux/rcupdate.h | 12 ++++++++++++
kernel/rcu/update.c | 12 ++++++++++++
3 files changed, 27 insertions(+)
diff -puN drivers/tty/sysrq.c~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs drivers/tty/sysrq.c
--- a/drivers/tty/sysrq.c~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs
+++ a/drivers/tty/sysrq.c
@@ -46,6 +46,7 @@
#include <linux/jiffies.h>
#include <linux/syscalls.h>
#include <linux/of.h>
+#include <linux/rcupdate.h>
#include <asm/ptrace.h>
#include <asm/irq_regs.h>
@@ -511,6 +512,7 @@ void __handle_sysrq(int key, bool check_
int orig_log_level;
int i;
+ rcu_sysrq_start();
rcu_read_lock();
/*
* Raise the apparent loglevel to maximum so that the sysrq header
@@ -554,6 +556,7 @@ void __handle_sysrq(int key, bool check_
console_loglevel = orig_log_level;
}
rcu_read_unlock();
+ rcu_sysrq_end();
}
void handle_sysrq(int key)
diff -puN include/linux/rcupdate.h~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs include/linux/rcupdate.h
--- a/include/linux/rcupdate.h~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs
+++ a/include/linux/rcupdate.h
@@ -228,6 +228,18 @@ void rcu_idle_exit(void);
void rcu_irq_enter(void);
void rcu_irq_exit(void);
+#ifdef CONFIG_RCU_STALL_COMMON
+void rcu_sysrq_start(void);
+void rcu_sysrq_end(void);
+#else /* #ifdef CONFIG_RCU_STALL_COMMON */
+static inline void rcu_sysrq_start(void)
+{
+}
+static inline void rcu_sysrq_end(void)
+{
+}
+#endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */
+
#ifdef CONFIG_RCU_USER_QS
void rcu_user_enter(void);
void rcu_user_exit(void);
diff -puN kernel/rcu/update.c~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs kernel/rcu/update.c
--- a/kernel/rcu/update.c~sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs
+++ a/kernel/rcu/update.c
@@ -320,6 +320,18 @@ int rcu_jiffies_till_stall_check(void)
return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
}
+void rcu_sysrq_start(void)
+{
+ if (!rcu_cpu_stall_suppress)
+ rcu_cpu_stall_suppress = 2;
+}
+
+void rcu_sysrq_end(void)
+{
+ if (rcu_cpu_stall_suppress == 2)
+ rcu_cpu_stall_suppress = 0;
+}
+
static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
{
rcu_cpu_stall_suppress = 1;
_
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mm-page-writebackc-fix-divide-by-zero-in-pos_ratio_polynom-fix.patch
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x86-require-x86-64-for-automatic-numa-balancing.patch
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mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v2.patch
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smaps-redefine-callback-functions-for-page-table-walker.patch
clear_refs-redefine-callback-functions-for-page-table-walker.patch
pagemap-redefine-callback-functions-for-page-table-walker.patch
numa_maps-redefine-callback-functions-for-page-table-walker.patch
memcg-redefine-callback-functions-for-page-table-walker.patch
arch-powerpc-mm-subpage-protc-use-walk_page_vma-instead-of-walk_page_range.patch
pagewalk-remove-argument-hmask-from-hugetlb_entry.patch
mempolicy-apply-page-table-walker-on-queue_pages_range.patch
mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
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hugetlb-prep_compound_gigantic_page-drop-__init-marker.patch
hugetlb-add-hstate_is_gigantic.patch
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hugetlb-move-helpers-up-in-the-file.patch
hugetlb-add-support-for-gigantic-page-allocation-at-runtime.patch
mm-page_alloc-prevent-migrate_reserve-pages-from-being-misplaced.patch
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mm-compaction-clean-up-unused-code-lines.patch
mm-compaction-cleanup-isolate_freepages.patch
mm-compaction-cleanup-isolate_freepages-fix.patch
mm-compaction-cleanup-isolate_freepages-fix-2.patch
mm-swapc-clean-up-lru_cache_add-functions.patch
mm-numa-add-migrated-transhuge-pages-to-lru-the-same-way-as-base-pages.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
sysrq-rcu-ify-__handle_sysrq.patch
sysrqrcu-suppress-rcu-stall-warnings-while-sysrq-runs.patch
linux-next.patch
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