After running some of the libhugetlbfs tests the value for /proc/meminfo/HugePages_Rsvd becomes really large. It looks like it has wrapped backwards from zero. Below is the sequence I used to run one of the tests that causes this; the tests passes for what it is intended to test but leaves a large value for reserved pages and that seemed strange to me. test run on ppc64 with 16M huge pages cat /proc/meminfo .... HugePages_Total: 25 HugePages_Free: 25 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB mount -t hugetlbfs hugetlbfs /mnt tundro4:~/libhugetlbfs-dev-20080516/tests # HUGETLBFS_VERBOSE=99 HUGETLBFS_DEBUG=y PATH="obj64:$PATH" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:../obj64:obj64" truncate_above_4GB Starting testcase "truncate_above_4GB", pid 3145 Mapping 3 hpages at offset 0x100000000...mapped at 0x3fffd000000 Replacing map at 0x3ffff000000 with map from offset 0x1000000...done Truncating at 0x100000000...done PASS cat /proc/meminfo .... HugePages_Total: 25 HugePages_Free: 25 HugePages_Rsvd: 18446744073709551614 HugePages_Surp: 0 Hugepagesize: 16384 kB I put in some printks and see that the rsvd value goes mad in 'return_unused_surplus_pages'. Debug output: tundro4 kernel: mm/hugetlb.c:gather_surplus_pages:527; resv_huge_pages=0 delta=3 tundro4 kernel: Call Trace: tundro4 kernel: [c000000287dff9a0] [c000000000010978] .show_stack+0x7c/0x1c4 (unreliable) tundro4 kernel: [c000000287dffa50] [c0000000000d7c8c] .hugetlb_acct_memory+0xa4/0x448 tundro4 kernel: [c000000287dffb20] [c0000000000d85ec] .hugetlb_reserve_pages+0xec/0x16c tundro4 kernel: [c000000287dffbc0] [c0000000001be7fc] .hugetlbfs_file_mmap+0xe0/0x154 tundro4 kernel: [c000000287dffc70] [c0000000000cbc78] .mmap_region+0x280/0x52c tundro4 kernel: [c000000287dffd80] [c00000000000bfa0] .sys_mmap+0xa8/0x108 tundro4 kernel: [c000000287dffe30] [c0000000000086ac] syscall_exit+0x0/0x40 tundro4 kernel: mm/hugetlb.c:gather_surplus_pages:530; resv_huge_pages=3 delta=3 tundro4 kernel: mm/hugetlb.c:decrement_hugepage_resv_vma:147; resv_huge_pages=3 tundro4 kernel: mm/hugetlb.c:decrement_hugepage_resv_vma:149; resv_huge_pages=2 tundro4 kernel: mm/hugetlb.c:return_unused_surplus_pages:630; resv_huge_pages=2 unused_resv_pages=2 tundro4 kernel: Call Trace: tundro4 kernel: [c000000287dff900] [c000000000010978] .show_stack+0x7c/0x1c4 (unreliable) tundro4 kernel: [c000000287dff9b0] [c0000000000d7a10] .return_unused_surplus_pages+0x70/0x248 tundro4 kernel: [c000000287dffa50] [c0000000000d7fb8] .hugetlb_acct_memory+0x3d0/0x448 tundro4 kernel: [c000000287dffb20] [c0000000000c98fc] .remove_vma+0x64/0xe0 tundro4 kernel: [c000000287dffbb0] [c0000000000cb058] .do_munmap+0x30c/0x354 tundro4 kernel: [c000000287dffc70] [c0000000000cbad0] .mmap_region+0xd8/0x52c tundro4 kernel: [c000000287dffd80] [c00000000000bfa0] .sys_mmap+0xa8/0x108 tundro4 kernel: [c000000287dffe30] [c0000000000086ac] syscall_exit+0x0/0x40 tundro4 kernel: mm/hugetlb.c:return_unused_surplus_pages:633; resv_huge_pages=0 unused_resv_pages=2 tundro4 kernel: mm/hugetlb.c:gather_surplus_pages:527; resv_huge_pages=0 delta=1 tundro4 kernel: Call Trace: tundro4 kernel: [c000000287dff9a0] [c000000000010978] .show_stack+0x7c/0x1c4 (unreliable) tundro4 kernel: [c000000287dffa50] [c0000000000d7c8c] .hugetlb_acct_memory+0xa4/0x448 tundro4 kernel: [c000000287dffb20] [c0000000000d85ec] .hugetlb_reserve_pages+0xec/0x16c tundro4 kernel: [c000000287dffbc0] [c0000000001be7fc] .hugetlbfs_file_mmap+0xe0/0x154 tundro4 kernel: [c000000287dffc70] [c0000000000cbc78] .mmap_region+0x280/0x52c tundro4 kernel: [c000000287dffd80] [c00000000000bfa0] .sys_mmap+0xa8/0x108 tundro4 kernel: [c000000287dffe30] [c0000000000086ac] syscall_exit+0x0/0x40 tundro4 kernel: mm/hugetlb.c:gather_surplus_pages:530; resv_huge_pages=1 delta=1 tundro4 kernel: mm/hugetlb.c:decrement_hugepage_resv_vma:147; resv_huge_pages=1 tundro4 kernel: mm/hugetlb.c:decrement_hugepage_resv_vma:149; resv_huge_pages=0 tundro4 kernel: mm/hugetlb.c:return_unused_surplus_pages:630; resv_huge_pages=0 unused_resv_pages=2 tundro4 kernel: Call Trace: tundro4 kernel: [c000000287dff860] [c000000000010978] .show_stack+0x7c/0x1c4 (unreliable) tundro4 kernel: [c000000287dff910] [c0000000000d7a10] .return_unused_surplus_pages+0x70/0x248 tundro4 kernel: [c000000287dff9b0] [c0000000000d7fb8] .hugetlb_acct_memory+0x3d0/0x448 tundro4 kernel: [c000000287dffa80] [c0000000000c98fc] .remove_vma+0x64/0xe0 tundro4 kernel: [c000000287dffb10] [c0000000000c9af0] .exit_mmap+0x178/0x1b8 tundro4 kernel: [c000000287dffbc0] [c000000000055ef0] .mmput+0x60/0x178 tundro4 kernel: [c000000287dffc50] [c00000000005add8] .exit_mm+0x130/0x154 tundro4 kernel: [c000000287dffce0] [c00000000005d598] .do_exit+0x2bc/0x778 tundro4 kernel: [c000000287dffda0] [c00000000005db38] .sys_exit_group+0x0/0x8 tundro4 kernel: [c000000287dffe30] [c0000000000086ac] syscall_exit+0x0/0x40 tundro4 kernel: mm/hugetlb.c:return_unused_surplus_pages:633; resv_huge_pages=18446744073709551614 unused_resv_pages=2 ============the end=============== -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
