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    Subject[PATCH 07/30] mm: allow PF_MEMALLOC from softirq context
    Allow PF_MEMALLOC to be set in softirq context. 

    This is needed to allow network softirq packet processing to make use of
    PF_MEMALLOC.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    ---
    include/linux/sched.h | 7 +++++++
    kernel/softirq.c | 3 +++
    mm/page_alloc.c | 7 ++++---
    3 files changed, 14 insertions(+), 3 deletions(-)

    Index: linux-2.6/mm/page_alloc.c
    ===================================================================
    --- linux-2.6.orig/mm/page_alloc.c
    +++ linux-2.6/mm/page_alloc.c
    @@ -1542,9 +1542,10 @@ int gfp_to_alloc_flags(gfp_t gfp_mask)
    alloc_flags |= ALLOC_HARDER;

    if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
    - if (!in_interrupt() &&
    - ((p->flags & PF_MEMALLOC) ||
    - unlikely(test_thread_flag(TIF_MEMDIE))))
    + if (!in_irq() && (p->flags & PF_MEMALLOC))
    + alloc_flags |= ALLOC_NO_WATERMARKS;
    + else if (!in_interrupt() &&
    + unlikely(test_thread_flag(TIF_MEMDIE)))
    alloc_flags |= ALLOC_NO_WATERMARKS;
    }

    Index: linux-2.6/kernel/softirq.c
    ===================================================================
    --- linux-2.6.orig/kernel/softirq.c
    +++ linux-2.6/kernel/softirq.c
    @@ -213,6 +213,8 @@ asmlinkage void __do_softirq(void)
    __u32 pending;
    int max_restart = MAX_SOFTIRQ_RESTART;
    int cpu;
    + unsigned long pflags = current->flags;
    + current->flags &= ~PF_MEMALLOC;

    pending = local_softirq_pending();
    account_system_vtime(current);
    @@ -251,6 +253,7 @@ restart:

    account_system_vtime(current);
    _local_bh_enable();
    + tsk_restore_flags(current, pflags, PF_MEMALLOC);
    }

    #ifndef __ARCH_HAS_DO_SOFTIRQ
    Index: linux-2.6/include/linux/sched.h
    ===================================================================
    --- linux-2.6.orig/include/linux/sched.h
    +++ linux-2.6/include/linux/sched.h
    @@ -1501,6 +1501,13 @@ static inline void put_task_struct(struc
    #define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
    #define used_math() tsk_used_math(current)

    +static inline void tsk_restore_flags(struct task_struct *p,
    + unsigned long pflags, unsigned long mask)
    +{
    + p->flags &= ~mask;
    + p->flags |= pflags & mask;
    +}
    +
    #ifdef CONFIG_SMP
    extern int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask);
    #else
    --



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