• Wanpeng Li's avatar
    mm/hugetlb: fix total hugetlbfs pages count when using memory overcommit accouting · d0028588
    Wanpeng Li authored
    hugetlb_total_pages is used for overcommit calculations but the current
    implementation considers only the default hugetlb page size (which is
    either the first defined hugepage size or the one specified by
    default_hugepagesz kernel boot parameter).
    
    If the system is configured for more than one hugepage size, which is
    possible since commit a137e1cc ("hugetlbfs: per mount huge page
    sizes") then the overcommit estimation done by __vm_enough_memory()
    (resp.  shown by meminfo_proc_show) is not precise - there is an
    impression of more available/allowed memory.  This can lead to an
    unexpected ENOMEM/EFAULT resp.  SIGSEGV when memory is accounted.
    
    Testcase:
      boot: hugepagesz=1G hugepages=1
      the default overcommit ratio is 50
      before patch:
    
        egrep 'CommitLimit' /proc/meminfo
        CommitLimit:     55434168 kB
    
      after patch:
    
        egrep 'CommitLimit' /proc/meminfo
        CommitLimit:     54909880 kB
    
    [akpm@linux-foundation.org: coding-style tweak]
    Signed-off-by: default avatarWanpeng Li <liwanp@linux.vnet.ibm.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
    Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
    Cc: Hillf Danton <dhillf@gmail.com>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: <stable@vger.kernel.org>		[3.0+]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d0028588
hugetlb.c 82.4 KB