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authorYang Shi <yang@os.amperecomputing.com>2023-12-20 22:59:43 -0800
committerAndrew Morton <akpm@linux-foundation.org>2024-01-25 23:52:20 -0800
commitc4608d1bf7c6536d1a3d233eb21e50678681564e (patch)
tree641888c2d653c4700733dd57821f30f09052fa9f
parent4dca82d14174fe53f656a6bc32398db1bdd8f481 (diff)
mm: mmap: map MAP_STACK to VM_NOHUGEPAGE
commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") incured regression for stress-ng pthread benchmark [1]. It is because THP get allocated to pthread's stack area much more possible than before. Pthread's stack area is allocated by mmap without VM_GROWSDOWN or VM_GROWSUP flag, so kernel can't tell whether it is a stack area or not. The MAP_STACK flag is used to mark the stack area, but it is a no-op on Linux. Mapping MAP_STACK to VM_NOHUGEPAGE to prevent from allocating THP for such stack area. With this change the stack area looks like: fffd18e10000-fffd19610000 rw-p 00000000 00:00 0 Size: 8192 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 12 kB Pss: 12 kB Pss_Dirty: 12 kB Shared_Clean: 0 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 12 kB Referenced: 12 kB Anonymous: 12 kB KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB THPeligible: 0 VmFlags: rd wr mr mw me ac nh The "nh" flag is set. [1] https://lore.kernel.org/linux-mm/202312192310.56367035-oliver.sang@intel.com/ Link: https://lkml.kernel.org/r/20231221065943.2803551-2-shy828301@gmail.com Fixes: efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") Signed-off-by: Yang Shi <yang@os.amperecomputing.com> Reported-by: kernel test robot <oliver.sang@intel.com> Tested-by: Oliver Sang <oliver.sang@intel.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> Cc: Rik van Riel <riel@surriel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Christopher Lameter <cl@linux.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: <stable@vger.kerenl.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--include/linux/mman.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 40d94411d492..dc7048824be8 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -156,6 +156,7 @@ calc_vm_flag_bits(unsigned long flags)
return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) |
_calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) |
_calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) |
+ _calc_vm_trans(flags, MAP_STACK, VM_NOHUGEPAGE) |
arch_calc_vm_flag_bits(flags);
}