--- /dev/null
+From stable+bounces-23367-greg=kroah.com@vger.kernel.org Thu Feb 22 18:06:34 2024
+From: Petr Vorel <pvorel@suse.cz>
+Date: Thu, 22 Feb 2024 18:05:40 +0100
+Subject: sched/rt: Disallow writing invalid values to sched_rt_period_us
+To: stable@vger.kernel.org
+Cc: Cyril Hrubis <chrubis@suse.cz>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sasha Levin <sashal@kernel.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Petr Vorel <pvorel@suse.cz>
+Message-ID: <20240222170540.1375962-3-pvorel@suse.cz>
+
+From: Cyril Hrubis <chrubis@suse.cz>
+
+[ Upstream commit 079be8fc630943d9fc70a97807feb73d169ee3fc ]
+
+The validation of the value written to sched_rt_period_us was broken
+because:
+
+ - the sysclt_sched_rt_period is declared as unsigned int
+ - parsed by proc_do_intvec()
+ - the range is asserted after the value parsed by proc_do_intvec()
+
+Because of this negative values written to the file were written into a
+unsigned integer that were later on interpreted as large positive
+integers which did passed the check:
+
+ if (sysclt_sched_rt_period <= 0)
+ return EINVAL;
+
+This commit fixes the parsing by setting explicit range for both
+perid_us and runtime_us into the sched_rt_sysctls table and processes
+the values with proc_dointvec_minmax() instead.
+
+Alternatively if we wanted to use full range of unsigned int for the
+period value we would have to split the proc_handler and use
+proc_douintvec() for it however even the
+Documentation/scheduller/sched-rt-group.rst describes the range as 1 to
+INT_MAX.
+
+As far as I can tell the only problem this causes is that the sysctl
+file allows writing negative values which when read back may confuse
+userspace.
+
+There is also a LTP test being submitted for these sysctl files at:
+
+ http://patchwork.ozlabs.org/project/ltp/patch/20230901144433.2526-1-chrubis@suse.cz/
+
+Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Link: https://lore.kernel.org/r/20231002115553.3007-2-chrubis@suse.cz
+[ pvorel: rebased for 4.19 ]
+Reviewed-by: Petr Vorel <pvorel@suse.cz>
+Signed-off-by: Petr Vorel <pvorel@suse.cz>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/rt.c | 5 +----
+ kernel/sysctl.c | 5 +++++
+ 2 files changed, 6 insertions(+), 4 deletions(-)
+
+--- a/kernel/sched/rt.c
++++ b/kernel/sched/rt.c
+@@ -2658,9 +2658,6 @@ static int sched_rt_global_constraints(v
+
+ static int sched_rt_global_validate(void)
+ {
+- if (sysctl_sched_rt_period <= 0)
+- return -EINVAL;
+-
+ if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
+ (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
+ return -EINVAL;
+@@ -2690,7 +2687,7 @@ int sched_rt_handler(struct ctl_table *t
+ old_period = sysctl_sched_rt_period;
+ old_runtime = sysctl_sched_rt_runtime;
+
+- ret = proc_dointvec(table, write, buffer, lenp, ppos);
++ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+ if (!ret && write) {
+ ret = sched_rt_global_validate();
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -127,6 +127,7 @@ static int zero;
+ static int __maybe_unused one = 1;
+ static int __maybe_unused two = 2;
+ static int __maybe_unused four = 4;
++static int int_max = INT_MAX;
+ static unsigned long zero_ul;
+ static unsigned long one_ul = 1;
+ static unsigned long long_max = LONG_MAX;
+@@ -464,6 +465,8 @@ static struct ctl_table kern_table[] = {
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = sched_rt_handler,
++ .extra1 = &one,
++ .extra2 = &int_max,
+ },
+ {
+ .procname = "sched_rt_runtime_us",
+@@ -471,6 +474,8 @@ static struct ctl_table kern_table[] = {
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sched_rt_handler,
++ .extra1 = &neg_one,
++ .extra2 = &int_max,
+ },
+ {
+ .procname = "sched_rr_timeslice_ms",
--- /dev/null
+From stable+bounces-23365-greg=kroah.com@vger.kernel.org Thu Feb 22 18:06:32 2024
+From: Petr Vorel <pvorel@suse.cz>
+Date: Thu, 22 Feb 2024 18:05:38 +0100
+Subject: sched/rt: Fix sysctl_sched_rr_timeslice intial value
+To: stable@vger.kernel.org
+Cc: Cyril Hrubis <chrubis@suse.cz>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sasha Levin <sashal@kernel.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Petr Vorel <pvorel@suse.cz>, Mel Gorman <mgorman@suse.de>
+Message-ID: <20240222170540.1375962-1-pvorel@suse.cz>
+
+From: Cyril Hrubis <chrubis@suse.cz>
+
+[ Upstream commit c7fcb99877f9f542c918509b2801065adcaf46fa ]
+
+There is a 10% rounding error in the intial value of the
+sysctl_sched_rr_timeslice with CONFIG_HZ_300=y.
+
+This was found with LTP test sched_rr_get_interval01:
+
+sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
+sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
+sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
+sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
+sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
+sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
+
+What this test does is to compare the return value from the
+sched_rr_get_interval() and the sched_rr_timeslice_ms sysctl file and
+fails if they do not match.
+
+The problem it found is the intial sysctl file value which was computed as:
+
+static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
+
+which works fine as long as MSEC_PER_SEC is multiple of HZ, however it
+introduces 10% rounding error for CONFIG_HZ_300:
+
+(MSEC_PER_SEC / HZ) * (100 * HZ / 1000)
+
+(1000 / 300) * (100 * 300 / 1000)
+
+3 * 30 = 90
+
+This can be easily fixed by reversing the order of the multiplication
+and division. After this fix we get:
+
+(MSEC_PER_SEC * (100 * HZ / 1000)) / HZ
+
+(1000 * (100 * 300 / 1000)) / 300
+
+(1000 * 30) / 300 = 100
+
+Fixes: 975e155ed873 ("sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds")
+Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Reviewed-by: Petr Vorel <pvorel@suse.cz>
+Acked-by: Mel Gorman <mgorman@suse.de>
+Tested-by: Petr Vorel <pvorel@suse.cz>
+Link: https://lore.kernel.org/r/20230802151906.25258-2-chrubis@suse.cz
+[ pvorel: rebased for 4.19 ]
+Signed-off-by: Petr Vorel <pvorel@suse.cz>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/rt.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/kernel/sched/rt.c
++++ b/kernel/sched/rt.c
+@@ -8,7 +8,7 @@
+ #include "pelt.h"
+
+ int sched_rr_timeslice = RR_TIMESLICE;
+-int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
++int sysctl_sched_rr_timeslice = (MSEC_PER_SEC * RR_TIMESLICE) / HZ;
+
+ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
+
--- /dev/null
+From stable+bounces-23366-greg=kroah.com@vger.kernel.org Thu Feb 22 18:06:37 2024
+From: Petr Vorel <pvorel@suse.cz>
+Date: Thu, 22 Feb 2024 18:05:39 +0100
+Subject: sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset
+To: stable@vger.kernel.org
+Cc: Cyril Hrubis <chrubis@suse.cz>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sasha Levin <sashal@kernel.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Petr Vorel <pvorel@suse.cz>, Mel Gorman <mgorman@suse.de>
+Message-ID: <20240222170540.1375962-2-pvorel@suse.cz>
+
+From: Cyril Hrubis <chrubis@suse.cz>
+
+[ Upstream commit c1fc6484e1fb7cc2481d169bfef129a1b0676abe ]
+
+The sched_rr_timeslice can be reset to default by writing value that is
+<= 0. However after reading from this file we always got the last value
+written, which is not useful at all.
+
+$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
+$ cat /proc/sys/kernel/sched_rr_timeslice_ms
+-1
+
+Fix this by setting the variable that holds the sysctl file value to the
+jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.
+
+Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Reviewed-by: Petr Vorel <pvorel@suse.cz>
+Acked-by: Mel Gorman <mgorman@suse.de>
+Tested-by: Petr Vorel <pvorel@suse.cz>
+Link: https://lore.kernel.org/r/20230802151906.25258-3-chrubis@suse.cz
+Signed-off-by: Petr Vorel <pvorel@suse.cz>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/rt.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/kernel/sched/rt.c
++++ b/kernel/sched/rt.c
+@@ -2735,6 +2735,9 @@ int sched_rr_handler(struct ctl_table *t
+ sched_rr_timeslice =
+ sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
+ msecs_to_jiffies(sysctl_sched_rr_timeslice);
++
++ if (sysctl_sched_rr_timeslice <= 0)
++ sysctl_sched_rr_timeslice = jiffies_to_msecs(RR_TIMESLICE);
+ }
+ mutex_unlock(&mutex);
+
memcg-add-refcnt-for-pcpu-stock-to-avoid-uaf-problem-in-drain_all_stock.patch
nilfs2-replace-warn_ons-for-invalid-dat-metadata-block-requests.patch
userfaultfd-fix-mmap_changing-checking-in-mfill_atomic_hugetlb.patch
+sched-rt-fix-sysctl_sched_rr_timeslice-intial-value.patch
+sched-rt-sysctl_sched_rr_timeslice-show-default-timeslice-after-reset.patch
+sched-rt-disallow-writing-invalid-values-to-sched_rt_period_us.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
