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Commit 76ebd054 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: introduce page pool in cpa 



DEBUG_PAGEALLOC was not possible on 64-bit due to its early-bootup
hardcoded reliance on PSE pages, and the unrobustness of the runtime
splitup of large pages. The splitup ended in recursive calls to
alloc_pages() when a page for a pte split was requested.

Avoid the recursion with a preallocated page pool, which is used to
split up large mappings and gets refilled in the return path of
kernel_map_pages after the split has been done. The size of the page
pool is adjusted to the available memory.

This part just implements the page pool and the initialization w/o
using it yet.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a03c2a48

arch/x86/mm/init_32.c

+2 −0
Original line number Diff line number Diff line
@@ -664,6 +664,8 @@ void __init mem_init(void) 
	if (boot_cpu_data.wp_works_ok < 0)

		test_wp_bit();



	cpa_init();



	/*

	 * Subtle. SMP is doing it's boot stuff late (because it has to

	 * fork idle threads) - but it also needs low mappings for the

arch/x86/mm/init_64.c

+2 −0
Original line number Diff line number Diff line
@@ -528,6 +528,8 @@ void __init mem_init(void) 
		reservedpages << (PAGE_SHIFT-10),

		datasize >> 10,

		initsize >> 10);



	cpa_init();

}



void free_init_pages(char *what, unsigned long begin, unsigned long end)

arch/x86/mm/pageattr.c

+81 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/mm.h>

#include <linux/interrupt.h>



#include <asm/e820.h>

#include <asm/processor.h>
@@ -336,6 +337,77 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, 
	return do_split;

}



static LIST_HEAD(page_pool);

static unsigned long pool_size, pool_pages, pool_low;

static unsigned long pool_used, pool_failed, pool_refill;



static void cpa_fill_pool(void)

{

	struct page *p;

	gfp_t gfp = GFP_KERNEL;



	/* Do not allocate from interrupt context */

	if (in_irq() || irqs_disabled())

		return;

	/*

	 * Check unlocked. I does not matter when we have one more

	 * page in the pool. The bit lock avoids recursive pool

	 * allocations:

	 */

	if (pool_pages >= pool_size || test_and_set_bit_lock(0, &pool_refill))

		return;



#ifdef CONFIG_DEBUG_PAGEALLOC

	/*

	 * We could do:

	 * gfp = in_atomic() ? GFP_ATOMIC : GFP_KERNEL;

	 * but this fails on !PREEMPT kernels

	 */

	gfp =  GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;

#endif



	while (pool_pages < pool_size) {

		p = alloc_pages(gfp, 0);

		if (!p) {

			pool_failed++;

			break;

		}

		spin_lock_irq(&pgd_lock);

		list_add(&p->lru, &page_pool);

		pool_pages++;

		spin_unlock_irq(&pgd_lock);

	}

	clear_bit_unlock(0, &pool_refill);

}



#define SHIFT_MB		(20 - PAGE_SHIFT)

#define ROUND_MB_GB		((1 << 10) - 1)

#define SHIFT_MB_GB		10

#define POOL_PAGES_PER_GB	16



void __init cpa_init(void)

{

	struct sysinfo si;

	unsigned long gb;



	si_meminfo(&si);

	/*

	 * Calculate the number of pool pages:

	 *

	 * Convert totalram (nr of pages) to MiB and round to the next

	 * GiB. Shift MiB to Gib and multiply the result by

	 * POOL_PAGES_PER_GB:

	 */

	gb = ((si.totalram >> SHIFT_MB) + ROUND_MB_GB) >> SHIFT_MB_GB;

	pool_size = POOL_PAGES_PER_GB * gb;

	pool_low = pool_size;



	cpa_fill_pool();

	printk(KERN_DEBUG

	       "CPA: page pool initialized %lu of %lu pages preallocated\n",

	       pool_pages, pool_size);

}



static int split_large_page(pte_t *kpte, unsigned long address)

{

	unsigned long flags, pfn, pfninc = 1;
@@ -600,7 +672,7 @@ static int change_page_attr_set_clr(unsigned long addr, int numpages, 
	 * Check whether we really changed something:

	 */

	if (!cpa.flushtlb)

		return ret;

		goto out;



	/*

	 * No need to flush, when we did not set any of the caching
@@ -619,6 +691,8 @@ static int change_page_attr_set_clr(unsigned long addr, int numpages, 
	else

		cpa_flush_all(cache);



out:

	cpa_fill_pool();

	return ret;

}
@@ -772,6 +846,12 @@ void kernel_map_pages(struct page *page, int numpages, int enable) 
	 * but that can deadlock->flush only current cpu:

	 */

	__flush_tlb_all();



	/*

	 * Try to refill the page pool here. We can do this only after

	 * the tlb flush.

	 */

	cpa_fill_pool();

}

#endif

include/asm-x86/cacheflush.h

+2 −0
Original line number Diff line number Diff line
@@ -44,6 +44,8 @@ int set_memory_np(unsigned long addr, int numpages); 


void clflush_cache_range(void *addr, unsigned int size);



void cpa_init(void);



#ifdef CONFIG_DEBUG_RODATA

void mark_rodata_ro(void);

#endif