2.4.12-ac1

 mm

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla/mm/highmem.c linux.ac/mm/highmem.c
--- linux.vanilla/mm/highmem.c   Tue Sep 18 22:10:43 2001
+++ linux.ac/mm/highmem.c   Wed Oct 10 01:48:38 2001
@@ -46,7 +46,7 @@
 
    for (i = 0; i < LAST_PKMAP; i++) {
       struct page *page;
-
+      pte_t pte;
       /*
        * zero means we don't have anything to do,
        * >1 means that it is still in use. Only
@@ -56,21 +56,10 @@
       if (pkmap_count[i] != 1)
          continue;
       pkmap_count[i] = 0;
-
-      /* sanity check */
-      if (pte_none(pkmap_page_table[i]))
+      pte = ptep_get_and_clear(pkmap_page_table+i);
+      if (pte_none(pte))
          BUG();
-
-      /*
-       * Don't need an atomic fetch-and-clear op here;
-       * no-one has the page mapped, and cannot get at
-       * its virtual address (and hence PTE) without first
-       * getting the kmap_lock (which is held here).
-       * So no dangers, even with speculative execution.
-       */
-      page = pte_page(pkmap_page_table[i]);
-      pte_clear(&pkmap_page_table[i]);
-
+      page = pte_page(pte);
       page->virtual = NULL;
    }
    flush_tlb_all();
@@ -150,7 +139,6 @@
 {
    unsigned long vaddr;
    unsigned long nr;
-   int need_wakeup;
 
    spin_lock(&kmap_lock);
    vaddr = (unsigned long) page->virtual;
@@ -162,28 +150,13 @@
     * A count must never go down to zero
     * without a TLB flush!
     */
-   need_wakeup = 0;
    switch (--pkmap_count[nr]) {
    case 0:
       BUG();
    case 1:
-      /*
-       * Avoid an unnecessary wake_up() function call.
-       * The common case is pkmap_count[] == 1, but
-       * no waiters.
-       * The tasks queued in the wait-queue are guarded
-       * by both the lock in the wait-queue-head and by
-       * the kmap_lock.  As the kmap_lock is held here,
-       * no need for the wait-queue-head's lock.  Simply
-       * test if the queue is empty.
-       */
-      need_wakeup = waitqueue_active(&pkmap_map_wait);
+      wake_up(&pkmap_map_wait);
    }
    spin_unlock(&kmap_lock);
-
-   /* do wake-up, if needed, race-free outside of the spin lock */
-   if (need_wakeup)
-      wake_up(&pkmap_map_wait);
 }
 
 #define POOL_SIZE 32
@@ -209,12 +182,20 @@
 {
    struct page *p_from;
    char *vfrom;
+   unsigned long flags;
 
    p_from = from->b_page;
 
-   vfrom = kmap_atomic(p_from, KM_USER0);
+   /*
+    * Since this can be executed from IRQ context, reentrance
+    * on the same CPU must be avoided:
+    */
+   __save_flags(flags);
+   __cli();
+   vfrom = kmap_atomic(p_from, KM_BOUNCE_WRITE);
    memcpy(to->b_data, vfrom + bh_offset(from), to->b_size);
-   kunmap_atomic(vfrom, KM_USER0);
+   kunmap_atomic(vfrom, KM_BOUNCE_WRITE);
+   __restore_flags(flags);
 }
 
 static inline void copy_to_high_bh_irq (struct buffer_head *to,
@@ -328,14 +309,14 @@
    struct page *page;
 
 repeat_alloc:
-   page = alloc_page(GFP_NOHIGHIO);
+   page = alloc_page(GFP_NOIO);
    if (page)
       return page;
    /*
     * No luck. First, kick the VM so it doesnt idle around while
     * we are using up our emergency rations.
     */
-   wakeup_bdflush();
+   wakeup_bdflush(0);
 
    /*
     * Try to allocate from the emergency pool.
@@ -366,14 +347,14 @@
    struct buffer_head *bh;
 
 repeat_alloc:
-   bh = kmem_cache_alloc(bh_cachep, SLAB_NOHIGHIO);
+   bh = kmem_cache_alloc(bh_cachep, SLAB_NOIO);
    if (bh)
       return bh;
    /*
     * No luck. First, kick the VM so it doesnt idle around while
     * we are using up our emergency rations.
     */
-   wakeup_bdflush();
+   wakeup_bdflush(0);
 
    /*
     * Try to allocate from the emergency pool.