From: Greg Kroah-Hartman Date: Sun, 11 Aug 2024 15:59:52 +0000 (+0200) Subject: 5.10-stable patches X-Git-Tag: v6.1.105~113 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8e836ed2c072f5e9fbfe6a14ac065f3afe10e12a;p=thirdparty%2Fkernel%2Fstable-queue.git 5.10-stable patches added patches: sched-cputime-fix-mul_u64_u64_div_u64-precision-for-cputime.patch --- diff --git a/queue-5.10/sched-cputime-fix-mul_u64_u64_div_u64-precision-for-cputime.patch b/queue-5.10/sched-cputime-fix-mul_u64_u64_div_u64-precision-for-cputime.patch new file mode 100644 index 00000000000..7c23bd8b865 --- /dev/null +++ b/queue-5.10/sched-cputime-fix-mul_u64_u64_div_u64-precision-for-cputime.patch @@ -0,0 +1,58 @@ +From 77baa5bafcbe1b2a15ef9c37232c21279c95481c Mon Sep 17 00:00:00 2001 +From: Zheng Zucheng +Date: Fri, 26 Jul 2024 02:32:35 +0000 +Subject: sched/cputime: Fix mul_u64_u64_div_u64() precision for cputime + +From: Zheng Zucheng + +commit 77baa5bafcbe1b2a15ef9c37232c21279c95481c upstream. + +In extreme test scenarios: +the 14th field utime in /proc/xx/stat is greater than sum_exec_runtime, +utime = 18446744073709518790 ns, rtime = 135989749728000 ns + +In cputime_adjust() process, stime is greater than rtime due to +mul_u64_u64_div_u64() precision problem. +before call mul_u64_u64_div_u64(), +stime = 175136586720000, rtime = 135989749728000, utime = 1416780000. +after call mul_u64_u64_div_u64(), +stime = 135989949653530 + +unsigned reversion occurs because rtime is less than stime. +utime = rtime - stime = 135989749728000 - 135989949653530 + = -199925530 + = (u64)18446744073709518790 + +Trigger condition: + 1). User task run in kernel mode most of time + 2). ARM64 architecture + 3). TICK_CPU_ACCOUNTING=y + CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set + +Fix mul_u64_u64_div_u64() conversion precision by reset stime to rtime + +Fixes: 3dc167ba5729 ("sched/cputime: Improve cputime_adjust()") +Signed-off-by: Zheng Zucheng +Signed-off-by: Peter Zijlstra (Intel) +Cc: +Link: https://lkml.kernel.org/r/20240726023235.217771-1-zhengzucheng@huawei.com +Signed-off-by: Greg Kroah-Hartman +--- + kernel/sched/cputime.c | 6 ++++++ + 1 file changed, 6 insertions(+) + +--- a/kernel/sched/cputime.c ++++ b/kernel/sched/cputime.c +@@ -579,6 +579,12 @@ void cputime_adjust(struct task_cputime + } + + stime = mul_u64_u64_div_u64(stime, rtime, stime + utime); ++ /* ++ * Because mul_u64_u64_div_u64() can approximate on some ++ * achitectures; enforce the constraint that: a*b/(b+c) <= a. ++ */ ++ if (unlikely(stime > rtime)) ++ stime = rtime; + + update: + /* diff --git a/queue-5.10/series b/queue-5.10/series index f54adfd17b2..89df40339ae 100644 --- a/queue-5.10/series +++ b/queue-5.10/series @@ -288,3 +288,4 @@ media-uvcvideo-fix-the-bandwdith-quirk-on-usb-3.x.patch jbd2-avoid-memleak-in-jbd2_journal_write_metadata_bu.patch s390-sclp-prevent-release-of-buffer-in-i-o.patch sunrpc-fix-a-race-to-wake-a-sync-task.patch +sched-cputime-fix-mul_u64_u64_div_u64-precision-for-cputime.patch