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authorTejun Heo <tj@kernel.org>2012-04-27 10:54:35 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-12 09:32:05 -0700
commit4f9b82ae13a482026a83eafa307ca037131a54b3 (patch)
treeeeaa4a63eedb53fac9383a5d8fb22f8190d91274
parent318c686eb39d8587b67be613a652ea55dc701a58 (diff)
percpu, x86: don't use PMD_SIZE as embedded atom_size on 32bit
commit d5e28005a1d2e67833852f4c9ea8ec206ea3ff85 upstream. With the embed percpu first chunk allocator, x86 uses either PAGE_SIZE or PMD_SIZE for atom_size. PMD_SIZE is used when CPU supports PSE so that percpu areas are aligned to PMD mappings and possibly allow using PMD mappings in vmalloc areas in the future. Using larger atom_size doesn't waste actual memory; however, it does require larger vmalloc space allocation later on for !first chunks. With reasonably sized vmalloc area, PMD_SIZE shouldn't be a problem but x86_32 at this point is anything but reasonable in terms of address space and using larger atom_size reportedly leads to frequent percpu allocation failures on certain setups. As there is no reason to not use PMD_SIZE on x86_64 as vmalloc space is aplenty and most x86_64 configurations support PSE, fix the issue by always using PMD_SIZE on x86_64 and PAGE_SIZE on x86_32. v2: drop cpu_has_pse test and make x86_64 always use PMD_SIZE and x86_32 PAGE_SIZE as suggested by hpa. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Yanmin Zhang <yanmin.zhang@intel.com> Reported-by: ShuoX Liu <shuox.liu@intel.com> Acked-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <4F97BA98.6010001@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kernel/setup_percpu.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 71f4727da373..5a98aa272184 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -185,10 +185,22 @@ void __init setup_per_cpu_areas(void)
#endif
rc = -EINVAL;
if (pcpu_chosen_fc != PCPU_FC_PAGE) {
- const size_t atom_size = cpu_has_pse ? PMD_SIZE : PAGE_SIZE;
const size_t dyn_size = PERCPU_MODULE_RESERVE +
PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
+ size_t atom_size;
+ /*
+ * On 64bit, use PMD_SIZE for atom_size so that embedded
+ * percpu areas are aligned to PMD. This, in the future,
+ * can also allow using PMD mappings in vmalloc area. Use
+ * PAGE_SIZE on 32bit as vmalloc space is highly contended
+ * and large vmalloc area allocs can easily fail.
+ */
+#ifdef CONFIG_X86_64
+ atom_size = PMD_SIZE;
+#else
+ atom_size = PAGE_SIZE;
+#endif
rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
dyn_size, atom_size,
pcpu_cpu_distance,