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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 54aba3c..8106bba 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -664,6 +664,8 @@
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
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 620d2b6..b59fc23 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -528,6 +528,8 @@
reservedpages << (PAGE_SHIFT-10),
datasize >> 10,
initsize >> 10);
+
+ cpa_init();
}
void free_init_pages(char *what, unsigned long begin, unsigned long end)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index eb2a544..831462c 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -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 @@
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 @@
* 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 @@
else
cpa_flush_all(cache);
+out:
+ cpa_fill_pool();
return ret;
}
@@ -772,6 +846,12 @@
* 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