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authorPasha Tatashin <pasha.tatashin@soleen.com>2023-01-13 15:42:53 +0000
committerAndrew Morton <akpm@linux-foundation.org>2023-02-02 22:33:11 -0800
commit6189eb82f0aec8a877190bf52e629c687ed02773 (patch)
tree3eb6efd413832ef68f72750f89c7e327f71c1a99 /mm/page_ext.c
parent950fe885a89770619e315f9b46301eebf0aab7b3 (diff)
mm/page_ext: do not allocate space for page_ext->flags if not needed
There is 8 byte page_ext->flags field allocated per page whenever CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext uses flags. Therefore, check whether flags is needed at least by one user and if so allocate space for it. For example when page_table_check is enabled, on a machine with 128G of memory before the fix: [ 2.244288] allocated 536870912 bytes of page_ext after the fix: [ 2.160154] allocated 268435456 bytes of page_ext Also, add a kernel-doc comment before page_ext_operations that describes the fields, and remove check if need() is set, as that is now a required field. [pasha.tatashin@soleen.com: address comments from Mike Rapoport] Link: https://lkml.kernel.org/r/20230117202103.1412449-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20230113154253.92480-1-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Li Zhe <lizhe.67@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_ext.c')
-rw-r--r--mm/page_ext.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/page_ext.c b/mm/page_ext.c
index 4ee522fd381c..e2c22ffdbb81 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -71,6 +71,7 @@ static bool need_page_idle(void)
}
static struct page_ext_operations page_idle_ops __initdata = {
.need = need_page_idle,
+ .need_shared_flags = true,
};
#endif
@@ -86,7 +87,7 @@ static struct page_ext_operations *page_ext_ops[] __initdata = {
#endif
};
-unsigned long page_ext_size = sizeof(struct page_ext);
+unsigned long page_ext_size;
static unsigned long total_usage;
static struct page_ext *lookup_page_ext(const struct page *page);
@@ -106,7 +107,16 @@ static bool __init invoke_need_callbacks(void)
bool need = false;
for (i = 0; i < entries; i++) {
- if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
+ if (page_ext_ops[i]->need()) {
+ if (page_ext_ops[i]->need_shared_flags) {
+ page_ext_size = sizeof(struct page_ext);
+ break;
+ }
+ }
+ }
+
+ for (i = 0; i < entries; i++) {
+ if (page_ext_ops[i]->need()) {
page_ext_ops[i]->offset = page_ext_size;
page_ext_size += page_ext_ops[i]->size;
need = true;