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authorNicolai Stange <nicstange@gmail.com>2015-08-06 15:46:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-07 04:39:40 +0300
commitd3cd131d935ab3bab700491edbbd7cad4040ce50 (patch)
tree50d9755ae9dfbb3105761b3f87e37fe9454d7a1b
parent7ace99170789bc53cbb7e9e352d7a3851208fbcf (diff)
downloadlinux-stericsson-d3cd131d935ab3bab700491edbbd7cad4040ce50.tar.gz
mm, meminit: replace rwsem with completion
Commit 0e1cc95b4cc7 ("mm: meminit: finish initialisation of struct pages before basic setup") introduced a rwsem to signal completion of the initialization workers. Lockdep complains about possible recursive locking: ============================================= [ INFO: possible recursive locking detected ] 4.1.0-12802-g1dc51b8 #3 Not tainted --------------------------------------------- swapper/0/1 is trying to acquire lock: (pgdat_init_rwsem){++++.+}, at: [<ffffffff8424c7fb>] page_alloc_init_late+0xc7/0xe6 but task is already holding lock: (pgdat_init_rwsem){++++.+}, at: [<ffffffff8424c772>] page_alloc_init_late+0x3e/0xe6 Replace the rwsem by a completion together with an atomic "outstanding work counter". [peterz@infradead.org: Barrier removal on the grounds of being pointless] [mgorman@suse.de: Applied review feedback] Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Alex Ng <alexng@microsoft.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ea0e6a6e7a11..322628278ae4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -18,7 +18,6 @@
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
-#include <linux/rwsem.h>
#include <linux/pagemap.h>
#include <linux/jiffies.h>
#include <linux/bootmem.h>
@@ -1060,7 +1059,15 @@ static void __init deferred_free_range(struct page *page,
__free_pages_boot_core(page, pfn, 0);
}
-static __initdata DECLARE_RWSEM(pgdat_init_rwsem);
+/* Completion tracking for deferred_init_memmap() threads */
+static atomic_t pgdat_init_n_undone __initdata;
+static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
+
+static inline void __init pgdat_init_report_one_done(void)
+{
+ if (atomic_dec_and_test(&pgdat_init_n_undone))
+ complete(&pgdat_init_all_done_comp);
+}
/* Initialise remaining memory on a node */
static int __init deferred_init_memmap(void *data)
@@ -1077,7 +1084,7 @@ static int __init deferred_init_memmap(void *data)
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
if (first_init_pfn == ULONG_MAX) {
- up_read(&pgdat_init_rwsem);
+ pgdat_init_report_one_done();
return 0;
}
@@ -1177,7 +1184,8 @@ free_range:
pr_info("node %d initialised, %lu pages in %ums\n", nid, nr_pages,
jiffies_to_msecs(jiffies - start));
- up_read(&pgdat_init_rwsem);
+
+ pgdat_init_report_one_done();
return 0;
}
@@ -1185,14 +1193,14 @@ void __init page_alloc_init_late(void)
{
int nid;
+ /* There will be num_node_state(N_MEMORY) threads */
+ atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
for_each_node_state(nid, N_MEMORY) {
- down_read(&pgdat_init_rwsem);
kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
}
/* Block until all are initialised */
- down_write(&pgdat_init_rwsem);
- up_write(&pgdat_init_rwsem);
+ wait_for_completion(&pgdat_init_all_done_comp);
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */