Re: [ANNOUNCE] 3.6.11-rt29

[Paul Gortmaker]

On Wed, Feb 13, 2013 at 9:13 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> Dear RT Folks,
>
> I'm pleased to announce the 3.6.11-rt29 release.
>
> Changes since 3.6.11-rt26:
>
>    1) Fix the RT highmem implementation on x86 this time really. The
>       issue I was seeing with kmap_atomic and friends was actually
>       when CONFIG_HIGHMEM was disabled. x8632 uses the atomic maps for
>       io_mapping_map_atomic_wc() even when CONFIG_HIGHMEM is off.
>
>    2) Modify the kmap_atomic per thread storage mechanism to reduce
>       code in switch_to
>    3) Rewrite RT highmem support for ARM with the kmap_atomic switch
>       mechanism like x86_32 uses it.
>
> This is probably the last release for 3.6 from my side. Steven might
> keep it maintained until the 3.8-rt stabilizes, but that's not yet
> decided.

I happened to notice that there was a misplaced dependency, that had
existed long before 3.6 trees.  It was meant for RCU's Kconfig item
"PREEMPT_RCU" but got accidentally placed under the Kconfig
"RT_GROUP_SCHED" option.  The fixup can be had by fetching:

git://git.kernel.org/pub/scm/linux/kernel/git/paulg/3.6-rt-patches.git

on branch "v3.6.11-rt29-fixes",  Unless you have been making your
own custom kernels, this change probably does not impact you.

Thanks,
Paul.
--


>
> The delta patch against 3.6.11-rt28 is appended below and can be found
> here:
>
>   http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/incr/patch-3.6.11-rt28-rt29.patch.xz
>
> The RT patch against 3.6.11 can be found here:
>
>   http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patch-3.6.11-rt29.patch.xz
>
> The split quilt queue is available at:
>
>   http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patches-3.6.11-rt29.tar.xz
>
> Enjoy,
>
>         tglx
>
> ------------->
> Index: linux-stable/arch/arm/include/asm/highmem.h
> ===================================================================
> --- linux-stable.orig/arch/arm/include/asm/highmem.h
> +++ linux-stable/arch/arm/include/asm/highmem.h
> @@ -57,25 +57,10 @@ static inline void *kmap_high_get(struct
>  #ifdef CONFIG_HIGHMEM
>  extern void *kmap(struct page *page);
>  extern void kunmap(struct page *page);
> -# ifndef CONFIG_PREEMPT_RT_FULL
>  extern void *kmap_atomic(struct page *page);
>  extern void __kunmap_atomic(void *kvaddr);
>  extern void *kmap_atomic_pfn(unsigned long pfn);
>  extern struct page *kmap_atomic_to_page(const void *ptr);
> -# else
> -#  define kmap_atomic(page)    \
> -       ({ pagefault_disable(); kmap(page); })
> -
> -#  define kmap_atomic_pfn(pfn) \
> -       ({ pagefault_disable(); kmap(pfn_to_page(pfn)) })
> -
> -#  define __kunmap_atomic(kvaddr)      \
> -       do { kunmap(kmap_to_page(kvaddr)); pagefault_enable(); } while(0)
> -
> -#  define kmap_atomic_to_page(kvaddr)  \
> -       kmap_to_page(kvaddr)
> -
> -# endif
>  #endif
>
>  #endif
> Index: linux-stable/arch/arm/mm/highmem.c
> ===================================================================
> --- linux-stable.orig/arch/arm/mm/highmem.c
> +++ linux-stable/arch/arm/mm/highmem.c
> @@ -36,9 +36,9 @@ void kunmap(struct page *page)
>  }
>  EXPORT_SYMBOL(kunmap);
>
> -#ifndef CONFIG_PREEMPT_RT_FULL
>  void *kmap_atomic(struct page *page)
>  {
> +       pte_t pte = mk_pte(page, kmap_prot);
>         unsigned int idx;
>         unsigned long vaddr;
>         void *kmap;
> @@ -77,7 +77,10 @@ void *kmap_atomic(struct page *page)
>          * in place, so the contained TLB flush ensures the TLB is updated
>          * with the new mapping.
>          */
> -       set_top_pte(vaddr, mk_pte(page, kmap_prot));
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +       current->kmap_pte[type] = pte;
> +#endif
> +       set_top_pte(vaddr, pte);
>
>         return (void *)vaddr;
>  }
> @@ -111,6 +114,7 @@ EXPORT_SYMBOL(__kunmap_atomic);
>
>  void *kmap_atomic_pfn(unsigned long pfn)
>  {
> +       pte_t pte = pfn_pte(pfn, kmap_prot);
>         unsigned long vaddr;
>         int idx, type;
>
> @@ -122,7 +126,10 @@ void *kmap_atomic_pfn(unsigned long pfn)
>  #ifdef CONFIG_DEBUG_HIGHMEM
>         BUG_ON(!pte_none(get_top_pte(vaddr)));
>  #endif
> -       set_top_pte(vaddr, pfn_pte(pfn, kmap_prot));
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +       current->kmap_pte[type] = pte;
> +#endif
> +       set_top_pte(vaddr, pte);
>
>         return (void *)vaddr;
>  }
> @@ -136,4 +143,28 @@ struct page *kmap_atomic_to_page(const v
>
>         return pte_page(get_top_pte(vaddr));
>  }
> +
> +#if defined CONFIG_PREEMPT_RT_FULL
> +void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
> +{
> +       int i;
> +
> +       /*
> +        * Clear @prev's kmap_atomic mappings
> +        */
> +       for (i = 0; i < prev_p->kmap_idx; i++) {
> +               int idx = i + KM_TYPE_NR * smp_processor_id();
> +
> +               set_top_pte(__fix_to_virt(FIX_KMAP_BEGIN + idx), __pte(0));
> +       }
> +       /*
> +        * Restore @next_p's kmap_atomic mappings
> +        */
> +       for (i = 0; i < next_p->kmap_idx; i++) {
> +               int idx = i + KM_TYPE_NR * smp_processor_id();
> +
> +               set_top_pte(__fix_to_virt(FIX_KMAP_BEGIN + idx),
> +                           next_p->kmap_pte[i]);
> +       }
> +}
>  #endif
> Index: linux-stable/arch/x86/include/asm/highmem.h
> ===================================================================
> --- linux-stable.orig/arch/x86/include/asm/highmem.h
> +++ linux-stable/arch/x86/include/asm/highmem.h
> @@ -56,39 +56,16 @@ extern unsigned long highstart_pfn, high
>
>  extern void *kmap_high(struct page *page);
>  extern void kunmap_high(struct page *page);
> -extern void *kmap_high_prot(struct page *page, pgprot_t prot);
>
>  void *kmap(struct page *page);
>  void kunmap(struct page *page);
>
> -#ifndef CONFIG_PREEMPT_RT_FULL
>  void *kmap_atomic_prot(struct page *page, pgprot_t prot);
>  void *kmap_atomic(struct page *page);
>  void __kunmap_atomic(void *kvaddr);
>  void *kmap_atomic_pfn(unsigned long pfn);
>  void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot);
>  struct page *kmap_atomic_to_page(void *ptr);
> -#else
> -void *__kmap_prot(struct page *page, pgprot_t prot);
> -# define kmap_atomic(page)                     \
> -       ({ pagefault_disable(); kmap(page); })
> -
> -# define kmap_atomic_pfn(pfn)                  \
> -       ({ pagefault_disable(); kmap(pfn_to_page(pfn)) })
> -
> -# define __kunmap_atomic(kvaddr)               \
> -       do { kunmap(kmap_to_page(kvaddr)); pagefault_enable(); } while(0)
> -
> -# define kmap_atomic_prot(page, prot)          \
> -       ({ pagefault_disable(); __kmap_prot(page, prot); })
> -
> -# define kmap_atomic_prot_pfn(pfn, prot)       \
> -       ({ pagefault_disable(); __kmap_prot(pfn_to_page(pfn), prot); })
> -
> -# define kmap_atomic_to_page(kvaddr)           \
> -       kmap_to_page(kvaddr)
> -
> -#endif
>
>  #define flush_cache_kmaps()    do { } while (0)
>
> Index: linux-stable/arch/x86/kernel/process_32.c
> ===================================================================
> --- linux-stable.orig/arch/x86/kernel/process_32.c
> +++ linux-stable/arch/x86/kernel/process_32.c
> @@ -198,6 +198,34 @@ start_thread(struct pt_regs *regs, unsig
>  }
>  EXPORT_SYMBOL_GPL(start_thread);
>
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +static void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
> +{
> +       int i;
> +
> +       /*
> +        * Clear @prev's kmap_atomic mappings
> +        */
> +       for (i = 0; i < prev_p->kmap_idx; i++) {
> +               int idx = i + KM_TYPE_NR * smp_processor_id();
> +               pte_t *ptep = kmap_pte - idx;
> +
> +               kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
> +       }
> +       /*
> +        * Restore @next_p's kmap_atomic mappings
> +        */
> +       for (i = 0; i < next_p->kmap_idx; i++) {
> +               int idx = i + KM_TYPE_NR * smp_processor_id();
> +
> +               set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
> +       }
> +}
> +#else
> +static inline void
> +switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) { }
> +#endif
> +
>
>  /*
>   *     switch_to(x,y) should switch tasks from x to y.
> @@ -277,40 +305,7 @@ __switch_to(struct task_struct *prev_p,
>                      task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
>                 __switch_to_xtra(prev_p, next_p, tss);
>
> -#if defined CONFIG_PREEMPT_RT_FULL && defined CONFIG_HIGHMEM
> -       /*
> -        * Save @prev's kmap_atomic stack
> -        */
> -       prev_p->kmap_idx = __this_cpu_read(__kmap_atomic_idx);
> -       if (unlikely(prev_p->kmap_idx)) {
> -               int i;
> -
> -               for (i = 0; i < prev_p->kmap_idx; i++) {
> -                       int idx = i + KM_TYPE_NR * smp_processor_id();
> -
> -                       pte_t *ptep = kmap_pte - idx;
> -                       prev_p->kmap_pte[i] = *ptep;
> -                       kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
> -               }
> -
> -               __this_cpu_write(__kmap_atomic_idx, 0);
> -       }
> -
> -       /*
> -        * Restore @next_p's kmap_atomic stack
> -        */
> -       if (unlikely(next_p->kmap_idx)) {
> -               int i;
> -
> -               __this_cpu_write(__kmap_atomic_idx, next_p->kmap_idx);
> -
> -               for (i = 0; i < next_p->kmap_idx; i++) {
> -                       int idx = i + KM_TYPE_NR * smp_processor_id();
> -
> -                       set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
> -               }
> -       }
> -#endif
> +       switch_kmaps(prev_p, next_p);
>
>         /*
>          * Leave lazy mode, flushing any hypercalls made here.
> Index: linux-stable/arch/x86/mm/highmem_32.c
> ===================================================================
> --- linux-stable.orig/arch/x86/mm/highmem_32.c
> +++ linux-stable/arch/x86/mm/highmem_32.c
> @@ -21,17 +21,6 @@ void kunmap(struct page *page)
>  }
>  EXPORT_SYMBOL(kunmap);
>
> -#ifdef CONFIF_PREEMPT_RT_FULL
> -void *__kmap_prot(struct page *page, pgprot_t prot)
> -{
> -       might_sleep();
> -       if (!PageHighMem(page))
> -               return page_address(page);
> -       return kmap_high_prot(page, prot);
> -}
> -#endif
> -
> -#ifndef CONFIG_PREEMPT_RT_FULL
>  /*
>   * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
>   * no global lock is needed and because the kmap code must perform a global TLB
> @@ -42,6 +31,7 @@ void *__kmap_prot(struct page *page, pgp
>   */
>  void *kmap_atomic_prot(struct page *page, pgprot_t prot)
>  {
> +       pte_t pte = mk_pte(page, prot);
>         unsigned long vaddr;
>         int idx, type;
>
> @@ -55,7 +45,10 @@ void *kmap_atomic_prot(struct page *page
>         idx = type + KM_TYPE_NR*smp_processor_id();
>         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>         WARN_ON(!pte_none(*(kmap_pte-idx)));
> -       set_pte(kmap_pte-idx, mk_pte(page, prot));
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +       current->kmap_pte[type] = pte;
> +#endif
> +       set_pte(kmap_pte-idx, pte);
>         arch_flush_lazy_mmu_mode();
>
>         return (void *)vaddr;
> @@ -126,7 +119,6 @@ struct page *kmap_atomic_to_page(void *p
>         return pte_page(*pte);
>  }
>  EXPORT_SYMBOL(kmap_atomic_to_page);
> -#endif
>
>  void __init set_highmem_pages_init(void)
>  {
> Index: linux-stable/include/linux/highmem.h
> ===================================================================
> --- linux-stable.orig/include/linux/highmem.h
> +++ linux-stable/include/linux/highmem.h
> @@ -7,6 +7,7 @@
>  #include <linux/mm.h>
>  #include <linux/uaccess.h>
>  #include <linux/hardirq.h>
> +#include <linux/sched.h>
>
>  #include <asm/cacheflush.h>
>
> @@ -59,8 +60,6 @@ static inline void *kmap(struct page *pa
>         return page_address(page);
>  }
>
> -#define __kmap_prot(page, prot)        kmap(page)
> -
>  static inline void kunmap(struct page *page)
>  {
>  }
> @@ -87,32 +86,49 @@ static inline void __kunmap_atomic(void
>
>  #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
>
> +#ifndef CONFIG_PREEMPT_RT_FULL
>  DECLARE_PER_CPU(int, __kmap_atomic_idx);
> +#endif
>
>  static inline int kmap_atomic_idx_push(void)
>  {
> +#ifndef CONFIG_PREEMPT_RT_FULL
>         int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1;
>
> -#ifdef CONFIG_DEBUG_HIGHMEM
> +# ifdef CONFIG_DEBUG_HIGHMEM
>         WARN_ON_ONCE(in_irq() && !irqs_disabled());
>         BUG_ON(idx > KM_TYPE_NR);
> -#endif
> +# endif
>         return idx;
> +#else
> +       return current->kmap_idx++;
> +#endif
>  }
>
>  static inline int kmap_atomic_idx(void)
>  {
> +#ifndef CONFIG_PREEMPT_RT_FULL
>         return __this_cpu_read(__kmap_atomic_idx) - 1;
> +#else
> +       return current->kmap_idx - 1;
> +#endif
>  }
>
>  static inline void kmap_atomic_idx_pop(void)
>  {
> -#ifdef CONFIG_DEBUG_HIGHMEM
> +#ifndef CONFIG_PREEMPT_RT_FULL
> +# ifdef CONFIG_DEBUG_HIGHMEM
>         int idx = __this_cpu_dec_return(__kmap_atomic_idx);
>
>         BUG_ON(idx < 0);
> -#else
> +# else
>         __this_cpu_dec(__kmap_atomic_idx);
> +# endif
> +#else
> +       current->kmap_idx--;
> +# ifdef CONFIG_DEBUG_HIGHMEM
> +       BUG_ON(current->kmap_idx < 0);
> +# endif
>  #endif
>  }
>
> Index: linux-stable/include/linux/sched.h
> ===================================================================
> --- linux-stable.orig/include/linux/sched.h
> +++ linux-stable/include/linux/sched.h
> @@ -1621,9 +1621,11 @@ struct task_struct {
>         int softirq_nestcnt;
>         unsigned int softirqs_raised;
>  #endif
> -#if defined CONFIG_PREEMPT_RT_FULL && defined CONFIG_HIGHMEM
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +# if defined CONFIG_HIGHMEM || defined CONFIG_X86_32
>         int kmap_idx;
>         pte_t kmap_pte[KM_TYPE_NR];
> +# endif
>  #endif
>
>  #ifdef CONFIG_DEBUG_PREEMPT
> Index: linux-stable/localversion-rt
> ===================================================================
> --- linux-stable.orig/localversion-rt
> +++ linux-stable/localversion-rt
> @@ -1 +1 @@
> --rt28
> +-rt29
> Index: linux-stable/mm/highmem.c
> ===================================================================
> --- linux-stable.orig/mm/highmem.c
> +++ linux-stable/mm/highmem.c
> @@ -29,10 +29,11 @@
>  #include <linux/kgdb.h>
>  #include <asm/tlbflush.h>
>
> -
> +#ifndef CONFIG_PREEMPT_RT_FULL
>  #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
>  DEFINE_PER_CPU(int, __kmap_atomic_idx);
>  #endif
> +#endif
>
>  /*
>   * Virtual_count is not a pure "count".
> @@ -47,8 +48,9 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
>  unsigned long totalhigh_pages __read_mostly;
>  EXPORT_SYMBOL(totalhigh_pages);
>
> -
> +#ifndef CONFIG_PREEMPT_RT_FULL
>  EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
> +#endif
>
>  unsigned int nr_free_highpages (void)
>  {
> @@ -157,7 +159,7 @@ void kmap_flush_unused(void)
>         unlock_kmap();
>  }
>
> -static inline unsigned long map_new_virtual(struct page *page, pgprot_t prot)
> +static inline unsigned long map_new_virtual(struct page *page)
>  {
>         unsigned long vaddr;
>         int count;
> @@ -199,7 +201,7 @@ start:
>         }
>         vaddr = PKMAP_ADDR(last_pkmap_nr);
>         set_pte_at(&init_mm, vaddr,
> -                  &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, prot));
> +                  &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
>
>         pkmap_count[last_pkmap_nr] = 1;
>         set_page_address(page, (void *)vaddr);
> @@ -215,7 +217,7 @@ start:
>   *
>   * We cannot call this from interrupts, as it may block.
>   */
> -void *kmap_high_prot(struct page *page, pgprot_t prot)
> +void *kmap_high(struct page *page)
>  {
>         unsigned long vaddr;
>
> @@ -226,26 +228,13 @@ void *kmap_high_prot(struct page *page,
>         lock_kmap();
>         vaddr = (unsigned long)page_address(page);
>         if (!vaddr)
> -               vaddr = map_new_virtual(page, prot);
> +               vaddr = map_new_virtual(page);
>         pkmap_count[PKMAP_NR(vaddr)]++;
>         BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
>         unlock_kmap();
>         return (void*) vaddr;
>  }
> -EXPORT_SYMBOL(kmap_high_prot);
>
> -/**
> - * kmap_high - map a highmem page into memory
> - * @page: &struct page to map
> - *
> - * Returns the page's virtual memory address.
> - *
> - * We cannot call this from interrupts, as it may block.
> - */
> -void *kmap_high(struct page *page)
> -{
> -       return kmap_high_prot(page, kmap_prot);
> -}
>  EXPORT_SYMBOL(kmap_high);
>
>  #ifdef ARCH_NEEDS_KMAP_HIGH_GET
> Index: linux-stable/arch/x86/mm/iomap_32.c
> ===================================================================
> --- linux-stable.orig/arch/x86/mm/iomap_32.c
> +++ linux-stable/arch/x86/mm/iomap_32.c
> @@ -56,6 +56,7 @@ EXPORT_SYMBOL_GPL(iomap_free);
>
>  void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
>  {
> +       pte_t pte = pfn_pte(pfn, prot);
>         unsigned long vaddr;
>         int idx, type;
>
> @@ -64,7 +65,10 @@ void *kmap_atomic_prot_pfn(unsigned long
>         type = kmap_atomic_idx_push();
>         idx = type + KM_TYPE_NR * smp_processor_id();
>         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
> -       set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +       current->kmap_pte[type] = pte;
> +#endif
> +       set_pte(kmap_pte - idx, pte);
>         arch_flush_lazy_mmu_mode();
>
>         return (void *)vaddr;
> Index: linux-stable/arch/arm/include/asm/switch_to.h
> ===================================================================
> --- linux-stable.orig/arch/arm/include/asm/switch_to.h
> +++ linux-stable/arch/arm/include/asm/switch_to.h
> @@ -3,6 +3,14 @@
>
>  #include <linux/thread_info.h>
>
> +#if defined CONFIG_PREEMPT_RT_FULL && defined CONFIG_HIGHMEM
> +void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p);
> +#else
> +static inline void
> +switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) { }
> +#endif
> +
> +
>  /*
>   * switch_to(prev, next) should switch from task `prev' to `next'
>   * `prev' will never be the same as `next'.  schedule() itself
> @@ -12,6 +20,7 @@ extern struct task_struct *__switch_to(s
>
>  #define switch_to(prev,next,last)                                      \
>  do {                                                                   \
> +       switch_kmaps(prev, next);                                       \
>         last = __switch_to(prev,task_thread_info(prev), task_thread_info(next));        \
>  } while (0)
>
> --
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