lkml.org 
[lkml]   [2019]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.19 134/192] sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
    Date
    From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>

    [ Upstream commit 1ca4fa3ab604734e38e2a3000c9abf788512ffa7 ]

    register_sched_domain_sysctl() copies the cpu_possible_mask into
    sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been
    allocated (ie, CONFIG_CPUMASK_OFFSTACK is set). However, when
    CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left
    uninitialized (all zeroes) and the kernel may fail to initialize
    sched_domain sysctl entries for all possible CPUs.

    This is visible to the user if the kernel is booted with maxcpus=n, or
    if ACPI tables have been modified to leave CPUs offline, and then
    checking for missing /proc/sys/kernel/sched_domain/cpu* entries.

    Fix this by separating the allocation and initialization, and adding a
    flag to initialize the possible CPU entries while system booting only.

    Tested-by: Syuuichirou Ishii <ishii.shuuichir@jp.fujitsu.com>
    Tested-by: Tarumizu, Kohei <tarumizu.kohei@jp.fujitsu.com>
    Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
    Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: https://lkml.kernel.org/r/20190129151245.5073-1-msys.mizuma@gmail.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/sched/debug.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
    index 6383aa6a60ca..141ea9ff210e 100644
    --- a/kernel/sched/debug.c
    +++ b/kernel/sched/debug.c
    @@ -315,6 +315,7 @@ void register_sched_domain_sysctl(void)
    {
    static struct ctl_table *cpu_entries;
    static struct ctl_table **cpu_idx;
    + static bool init_done = false;
    char buf[32];
    int i;

    @@ -344,7 +345,10 @@ void register_sched_domain_sysctl(void)
    if (!cpumask_available(sd_sysctl_cpus)) {
    if (!alloc_cpumask_var(&sd_sysctl_cpus, GFP_KERNEL))
    return;
    + }

    + if (!init_done) {
    + init_done = true;
    /* init to possible to not have holes in @cpu_entries */
    cpumask_copy(sd_sysctl_cpus, cpu_possible_mask);
    }
    --
    2.19.1
    \
     
     \ /
      Last update: 2019-03-27 20:02    [W:4.090 / U:0.316 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site