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Date: Tue, 28 Apr 2015 15:37:02 +0100
From: Mel Gorman <mgorman@...e.de>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Nathan Zimmer <nzimmer@....com>,
Dave Hansen <dave.hansen@...el.com>,
Waiman Long <waiman.long@...com>,
Scott Norton <scott.norton@...com>,
Daniel J Blueman <daniel@...ascale.com>,
Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 05/13] mm: meminit: Make __early_pfn_to_nid SMP-safe and introduce meminit_pfn_in_nid
__early_pfn_to_nid() use static variables to cache recent lookups as memblock
lookups are very expensive but it assumes that memory initialisation is
single-threaded. Parallel initialisation of struct pages will break that
assumption so this patch makes __early_pfn_to_nid() SMP-safe by requiring
the caller to cache recent search information. early_pfn_to_nid() keeps
the same interface but is only safe to use early in boot due to the use
of a global static variable. meminit_pfn_in_nid() is an SMP-safe version
that callers must maintain their own state for.
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
arch/ia64/mm/numa.c | 19 +++++++------------
include/linux/mm.h | 6 ++++--
include/linux/mmzone.h | 16 +++++++++++++++-
mm/page_alloc.c | 40 +++++++++++++++++++++++++---------------
4 files changed, 51 insertions(+), 30 deletions(-)
diff --git a/arch/ia64/mm/numa.c b/arch/ia64/mm/numa.c
index ea21d4cad540..aa19b7ac8222 100644
--- a/arch/ia64/mm/numa.c
+++ b/arch/ia64/mm/numa.c
@@ -58,27 +58,22 @@ paddr_to_nid(unsigned long paddr)
* SPARSEMEM to allocate the SPARSEMEM sectionmap on the NUMA node where
* the section resides.
*/
-int __meminit __early_pfn_to_nid(unsigned long pfn)
+int __meminit __early_pfn_to_nid(unsigned long pfn,
+ struct mminit_pfnnid_cache *state)
{
int i, section = pfn >> PFN_SECTION_SHIFT, ssec, esec;
- /*
- * NOTE: The following SMP-unsafe globals are only used early in boot
- * when the kernel is running single-threaded.
- */
- static int __meminitdata last_ssec, last_esec;
- static int __meminitdata last_nid;
- if (section >= last_ssec && section < last_esec)
- return last_nid;
+ if (section >= state->last_start && section < state->last_end)
+ return state->last_nid;
for (i = 0; i < num_node_memblks; i++) {
ssec = node_memblk[i].start_paddr >> PA_SECTION_SHIFT;
esec = (node_memblk[i].start_paddr + node_memblk[i].size +
((1L << PA_SECTION_SHIFT) - 1)) >> PA_SECTION_SHIFT;
if (section >= ssec && section < esec) {
- last_ssec = ssec;
- last_esec = esec;
- last_nid = node_memblk[i].nid;
+ state->last_start = ssec;
+ state->last_end = esec;
+ state->last_nid = node_memblk[i].nid;
return node_memblk[i].nid;
}
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b6f82a31028a..a8a8b161fd65 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1802,7 +1802,8 @@ extern void sparse_memory_present_with_active_regions(int nid);
#if !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) && \
!defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID)
-static inline int __early_pfn_to_nid(unsigned long pfn)
+static inline int __early_pfn_to_nid(unsigned long pfn,
+ struct mminit_pfnnid_cache *state)
{
return 0;
}
@@ -1810,7 +1811,8 @@ static inline int __early_pfn_to_nid(unsigned long pfn)
/* please see mm/page_alloc.c */
extern int __meminit early_pfn_to_nid(unsigned long pfn);
/* there is a per-arch backend function. */
-extern int __meminit __early_pfn_to_nid(unsigned long pfn);
+extern int __meminit __early_pfn_to_nid(unsigned long pfn,
+ struct mminit_pfnnid_cache *state);
#endif
extern void set_dma_reserve(unsigned long new_dma_reserve);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 2782df47101e..a67b33e52dfe 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1216,10 +1216,24 @@ void sparse_init(void);
#define sparse_index_init(_sec, _nid) do {} while (0)
#endif /* CONFIG_SPARSEMEM */
+/*
+ * During memory init memblocks map pfns to nids. The search is expensive and
+ * this caches recent lookups. The implementation of __early_pfn_to_nid
+ * may treat start/end as pfns or sections.
+ */
+struct mminit_pfnnid_cache {
+ unsigned long last_start;
+ unsigned long last_end;
+ int last_nid;
+};
+
#ifdef CONFIG_NODES_SPAN_OTHER_NODES
bool early_pfn_in_nid(unsigned long pfn, int nid);
+bool meminit_pfn_in_nid(unsigned long pfn, int node,
+ struct mminit_pfnnid_cache *state);
#else
-#define early_pfn_in_nid(pfn, nid) (1)
+#define early_pfn_in_nid(pfn, nid) (1)
+#define meminit_pfn_in_nid(pfn, nid, state) (1)
#endif
#ifndef early_pfn_valid
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a59f75d02d11..6c5ed5804e82 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4463,39 +4463,41 @@ int __meminit init_currently_empty_zone(struct zone *zone,
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
#ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
+
/*
* Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
*/
-int __meminit __early_pfn_to_nid(unsigned long pfn)
+int __meminit __early_pfn_to_nid(unsigned long pfn,
+ struct mminit_pfnnid_cache *state)
{
unsigned long start_pfn, end_pfn;
int nid;
- /*
- * NOTE: The following SMP-unsafe globals are only used early in boot
- * when the kernel is running single-threaded.
- */
- static unsigned long __meminitdata last_start_pfn, last_end_pfn;
- static int __meminitdata last_nid;
- if (last_start_pfn <= pfn && pfn < last_end_pfn)
- return last_nid;
+ if (state->last_start <= pfn && pfn < state->last_end)
+ return state->last_nid;
nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
if (nid != -1) {
- last_start_pfn = start_pfn;
- last_end_pfn = end_pfn;
- last_nid = nid;
+ state->last_start = start_pfn;
+ state->last_end = end_pfn;
+ state->last_nid = nid;
}
return nid;
}
#endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
+static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
+
+/* Only safe to use early in boot when initialisation is single-threaded */
int __meminit early_pfn_to_nid(unsigned long pfn)
{
int nid;
- nid = __early_pfn_to_nid(pfn);
+ /* The system will behave unpredictably otherwise */
+ BUG_ON(system_state != SYSTEM_BOOTING);
+
+ nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
if (nid >= 0)
return nid;
/* just returns 0 */
@@ -4503,15 +4505,23 @@ int __meminit early_pfn_to_nid(unsigned long pfn)
}
#ifdef CONFIG_NODES_SPAN_OTHER_NODES
-bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
+bool __meminit meminit_pfn_in_nid(unsigned long pfn, int node,
+ struct mminit_pfnnid_cache *state)
{
int nid;
- nid = __early_pfn_to_nid(pfn);
+ nid = __early_pfn_to_nid(pfn, state);
if (nid >= 0 && nid != node)
return false;
return true;
}
+
+/* Only safe to use early in boot when initialisation is single-threaded */
+bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
+{
+ return meminit_pfn_in_nid(pfn, node, &early_pfnnid_cache);
+}
+
#endif
/**
--
2.3.5
--
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