[patch] highmem-2.4.2-A0

[Ingo Molnar <mingo@elte.hu>]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 693 bytes --]


On Mon, 26 Feb 2001, Andrea Arcangeli wrote:

> The highmem changes in 2.4.2ac3 has a couple of bugs, one relevant
> that can generate deadlocks (re-enable interrupts with io_request_lock
> acquired).

oops, right, the emergency-pool patch was just a quick hack to check
whether this is the final problem affecting RL highmem systems.

the attached highmem-2.4.2-A0 patch does the jist of your fixes, against
-ac4. Differences: no need to complicate highmem.c with pool-fillup on
bootup. It will get refilled after the first disk-accesses anyway.

i'm unsure about the other changes done by your patch, could you explain
them? Notably the pgalloc-3level.h and fault.c changes. Thanks,

	Ingo

[-- Attachment #2: Type: TEXT/PLAIN, Size: 1705 bytes --]

--- linux/mm/highmem.c.orig	Mon Feb 26 23:33:17 2001
+++ linux/mm/highmem.c	Mon Feb 26 23:37:02 2001
@@ -217,6 +217,7 @@
 static inline void bounce_end_io (struct buffer_head *bh, int uptodate)
 {
 	struct page *page;
+	unsigned long flags;
 	struct list_head *tmp;
 	struct buffer_head *bh_orig = (struct buffer_head *)(bh->b_private);
 
@@ -231,27 +232,27 @@
 		__free_page(page);
 	else {
 		tmp = &emergency_pages;
-		spin_lock_irq(&emergency_lock);
+		spin_lock_irqsave(&emergency_lock, flags);
 		/*
 		 * We are abusing page->list to manage
 		 * the highmem emergency pool:
 		 */
 		list_add(&page->list, &emergency_pages);
 		nr_emergency_pages++;
-		spin_unlock_irq(&emergency_lock);
+		spin_unlock_irqrestore(&emergency_lock, flags);
 	}
 	
 	if (nr_emergency_pages >= POOL_SIZE)
 		kmem_cache_free(bh_cachep, bh);
 	else {
 		tmp = &emergency_bhs;
-		spin_lock_irq(&emergency_lock);
+		spin_lock_irqsave(&emergency_lock, flags);
 		/*
 		 * Ditto in the bh case, here we abuse b_inode_buffers:
 		 */
 		list_add(&bh->b_inode_buffers, &emergency_bhs);
 		nr_emergency_bhs++;
-		spin_unlock_irq(&emergency_lock);
+		spin_unlock_irqrestore(&emergency_lock, flags);
 	}
 }
 
@@ -297,6 +298,12 @@
 	spin_unlock_irq(&emergency_lock);
 	if (page)
 		return page;
+
+	run_task_queue(&tq_disk);
+
+	current->policy |= SCHED_YIELD;
+	__set_current_state(TASK_RUNNING);
+	schedule();
 	goto repeat_alloc;
 }
 
@@ -328,6 +335,12 @@
 	spin_unlock_irq(&emergency_lock);
 	if (bh)
 		return bh;
+
+	run_task_queue(&tq_disk);
+
+	current->policy |= SCHED_YIELD;
+	__set_current_state(TASK_RUNNING);
+	schedule();
 	goto repeat_alloc;
 }