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authorArun KS <arunks@codeaurora.org>2018-12-28 00:34:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 12:11:47 -0800
commit3d6357de8aa09e1966770dc1171c72679946464f (patch)
treea24bb2f8795ea4927c1ff64d5f5f00398bee925d /net
parentfecd4a50baaebf6bde7f9e0b88fef13ffe5d98a1 (diff)
mm: reference totalram_pages and managed_pages once per function
Patch series "mm: convert totalram_pages, totalhigh_pages and managed pages to atomic", v5. This series converts totalram_pages, totalhigh_pages and zone->managed_pages to atomic variables. totalram_pages, zone->managed_pages and totalhigh_pages updates are protected by managed_page_count_lock, but readers never care about it. Convert these variables to atomic to avoid readers potentially seeing a store tear. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 It seemes better to remove the lock and convert variables to atomic. With the change, preventing poteintial store-to-read tearing comes as a bonus. This patch (of 4): This is in preparation to a later patch which converts totalram_pages and zone->managed_pages to atomic variables. Please note that re-reading the value might lead to a different value and as such it could lead to unexpected behavior. There are no known bugs as a result of the current code but it is better to prevent from them in principle. Link: http://lkml.kernel.org/r/1542090790-21750-2-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/dccp/proto.c7
-rw-r--r--net/netfilter/nf_conntrack_core.c7
-rw-r--r--net/netfilter/xt_hashlimit.c5
-rw-r--r--net/sctp/protocol.c7
4 files changed, 15 insertions, 11 deletions
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 2cc5fbb1b29e..ff727ff61b5b 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -1131,6 +1131,7 @@ EXPORT_SYMBOL_GPL(dccp_debug);
static int __init dccp_init(void)
{
unsigned long goal;
+ unsigned long nr_pages = totalram_pages;
int ehash_order, bhash_order, i;
int rc;
@@ -1157,10 +1158,10 @@ static int __init dccp_init(void)
*
* The methodology is similar to that of the buffer cache.
*/
- if (totalram_pages >= (128 * 1024))
- goal = totalram_pages >> (21 - PAGE_SHIFT);
+ if (nr_pages >= (128 * 1024))
+ goal = nr_pages >> (21 - PAGE_SHIFT);
else
- goal = totalram_pages >> (23 - PAGE_SHIFT);
+ goal = nr_pages >> (23 - PAGE_SHIFT);
if (thash_entries)
goal = (thash_entries *
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index e87c21e47efe..5eb990830348 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2248,6 +2248,7 @@ static __always_inline unsigned int total_extension_size(void)
int nf_conntrack_init_start(void)
{
+ unsigned long nr_pages = totalram_pages;
int max_factor = 8;
int ret = -ENOMEM;
int i;
@@ -2267,11 +2268,11 @@ int nf_conntrack_init_start(void)
* >= 4GB machines have 65536 buckets.
*/
nf_conntrack_htable_size
- = (((totalram_pages << PAGE_SHIFT) / 16384)
+ = (((nr_pages << PAGE_SHIFT) / 16384)
/ sizeof(struct hlist_head));
- if (totalram_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
+ if (nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
nf_conntrack_htable_size = 65536;
- else if (totalram_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
+ else if (nr_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
nf_conntrack_htable_size = 16384;
if (nf_conntrack_htable_size < 32)
nf_conntrack_htable_size = 32;
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 28e27a32d9b9..88b520ba2abc 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -274,14 +274,15 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
struct xt_hashlimit_htable *hinfo;
const struct seq_operations *ops;
unsigned int size, i;
+ unsigned long nr_pages = totalram_pages;
int ret;
if (cfg->size) {
size = cfg->size;
} else {
- size = (totalram_pages << PAGE_SHIFT) / 16384 /
+ size = (nr_pages << PAGE_SHIFT) / 16384 /
sizeof(struct hlist_head);
- if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
+ if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
size = 8192;
if (size < 16)
size = 16;
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 9b277bd36d1a..a5b24182b3cc 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1368,6 +1368,7 @@ static __init int sctp_init(void)
int status = -EINVAL;
unsigned long goal;
unsigned long limit;
+ unsigned long nr_pages = totalram_pages;
int max_share;
int order;
int num_entries;
@@ -1426,10 +1427,10 @@ static __init int sctp_init(void)
* The methodology is similar to that of the tcp hash tables.
* Though not identical. Start by getting a goal size
*/
- if (totalram_pages >= (128 * 1024))
- goal = totalram_pages >> (22 - PAGE_SHIFT);
+ if (nr_pages >= (128 * 1024))
+ goal = nr_pages >> (22 - PAGE_SHIFT);
else
- goal = totalram_pages >> (24 - PAGE_SHIFT);
+ goal = nr_pages >> (24 - PAGE_SHIFT);
/* Then compute the page order for said goal */
order = get_order(goal);

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