lkml.org 
[lkml]   [2015]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.13.y-ckt 141/156] sparc32: destroy_context() and switch_mm() needs to disable interrupts.
    Date
    3.13.11-ckt19 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Andreas Larsson <andreas@gaisler.com>

    [ Upstream commit 66d0f7ec9f1038452178b1993fc07fd96d30fd38 ]

    Load balancing can be triggered in the critical sections protected by
    srmmu_context_spinlock in destroy_context() and switch_mm() and can hang
    the cpu waiting for the rq lock of another cpu that in turn has called
    switch_mm hangning on srmmu_context_spinlock leading to deadlock.

    So, disable interrupt while taking srmmu_context_spinlock in
    destroy_context() and switch_mm() so we don't deadlock.

    See also commit 77b838fa1ef0 ("[SPARC64]: destroy_context() needs to disable
    interrupts.")

    Signed-off-by: Andreas Larsson <andreas@gaisler.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    arch/sparc/mm/srmmu.c | 11 +++++++----
    1 file changed, 7 insertions(+), 4 deletions(-)

    diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
    index 869023a..769bf7f 100644
    --- a/arch/sparc/mm/srmmu.c
    +++ b/arch/sparc/mm/srmmu.c
    @@ -458,10 +458,12 @@ static void __init sparc_context_init(int numctx)
    void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm,
    struct task_struct *tsk)
    {
    + unsigned long flags;
    +
    if (mm->context == NO_CONTEXT) {
    - spin_lock(&srmmu_context_spinlock);
    + spin_lock_irqsave(&srmmu_context_spinlock, flags);
    alloc_context(old_mm, mm);
    - spin_unlock(&srmmu_context_spinlock);
    + spin_unlock_irqrestore(&srmmu_context_spinlock, flags);
    srmmu_ctxd_set(&srmmu_context_table[mm->context], mm->pgd);
    }

    @@ -986,14 +988,15 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)

    void destroy_context(struct mm_struct *mm)
    {
    + unsigned long flags;

    if (mm->context != NO_CONTEXT) {
    flush_cache_mm(mm);
    srmmu_ctxd_set(&srmmu_context_table[mm->context], srmmu_swapper_pg_dir);
    flush_tlb_mm(mm);
    - spin_lock(&srmmu_context_spinlock);
    + spin_lock_irqsave(&srmmu_context_spinlock, flags);
    free_context(mm->context);
    - spin_unlock(&srmmu_context_spinlock);
    + spin_unlock_irqrestore(&srmmu_context_spinlock, flags);
    mm->context = NO_CONTEXT;
    }
    }
    --
    1.9.1


    \
     
     \ /
      Last update: 2015-04-08 01:41    [W:4.069 / U:0.124 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site