When inspecting a vague code inside prctl(PR_SET_MM_MEM) call (which testing the RLIMIT_DATA value to figure out if we're allowed to assign new @start_brk, @brk, @start_data, @end_data from mm_struct) it's been commited that RLIMIT_DATA in a form it's implemented now doesn't do anything useful because most of user-space libraries use mmap() syscall for dynamic memory allocations.
So Linus suggested to convert RLIMIT_DATA rlimit into something suitable for anonymous memory accounting. Here we introduce new @anon_vm member into mm descriptor which is updated every vm_stat_account call. When mmap_region() is called we test if current RLIMIT_DATA limit is not exceeded. This should give a way to control the amount of anonymous memory allocated. p.s.: This rfc not for application, I would like to hear if I move in right direction in general. In particular I need to add hugetlb anon mappings here as well and update docs and etc. So comments are highly appreciated. CC: Quentin Casasnovas <[email protected]> CC: Vegard Nossum <[email protected]> CC: Linus Torvalds <[email protected]> CC: Willy Tarreau <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Kees Cook <[email protected]> CC: Vladimir Davydov <[email protected]> CC: Konstantin Khlebnikov <[email protected]> CC: Pavel Emelyanov <[email protected]> CC: Vladimir Davydov <[email protected]> CC: Peter Zijlstra <[email protected]> Signed-off-by: Cyrill Gorcunov <[email protected]> --- fs/proc/task_mmu.c | 2 ++ include/linux/mm_types.h | 1 + mm/mmap.c | 22 ++++++++++++++++++++++ 3 files changed, 25 insertions(+) Index: linux-ml.git/fs/proc/task_mmu.c =================================================================== --- linux-ml.git.orig/fs/proc/task_mmu.c +++ linux-ml.git/fs/proc/task_mmu.c @@ -53,6 +53,7 @@ void task_mem(struct seq_file *m, struct "VmHWM:\t%8lu kB\n" "VmRSS:\t%8lu kB\n" "VmData:\t%8lu kB\n" + "VmAnon:\t%8lu kB\n" "VmStk:\t%8lu kB\n" "VmExe:\t%8lu kB\n" "VmLib:\t%8lu kB\n" @@ -66,6 +67,7 @@ void task_mem(struct seq_file *m, struct hiwater_rss << (PAGE_SHIFT-10), total_rss << (PAGE_SHIFT-10), data << (PAGE_SHIFT-10), + mm->anon_vm << (PAGE_SHIFT-10), mm->stack_vm << (PAGE_SHIFT-10), text, lib, ptes >> 10, pmds >> 10, Index: linux-ml.git/include/linux/mm_types.h =================================================================== --- linux-ml.git.orig/include/linux/mm_types.h +++ linux-ml.git/include/linux/mm_types.h @@ -429,6 +429,7 @@ struct mm_struct { unsigned long shared_vm; /* Shared pages (files) */ unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE */ unsigned long stack_vm; /* VM_GROWSUP/DOWN */ + unsigned long anon_vm; /* Anonymous pages mapped */ unsigned long def_flags; unsigned long start_code, end_code, start_data, end_data; unsigned long start_brk, brk, start_stack; Index: linux-ml.git/mm/mmap.c =================================================================== --- linux-ml.git.orig/mm/mmap.c +++ linux-ml.git/mm/mmap.c @@ -1214,6 +1214,8 @@ void vm_stat_account(struct mm_struct *m { const unsigned long stack_flags = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); + const unsigned long not_anon_acc + = VM_GROWSUP | VM_GROWSDOWN | VM_SHARED | VM_MAYSHARE; mm->total_vm += pages; @@ -1223,6 +1225,9 @@ void vm_stat_account(struct mm_struct *m mm->exec_vm += pages; } else if (flags & stack_flags) mm->stack_vm += pages; + + if (!file && (flags & not_anon_acc) == 0) + mm->anon_vm += pages; } #endif /* CONFIG_PROC_FS */ @@ -1534,6 +1539,13 @@ static inline int accountable_mapping(st return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; } +static inline int anon_accountable_mapping(struct file *file, vm_flags_t vm_flags) +{ + return !file && + (vm_flags & (VM_GROWSDOWN | VM_GROWSUP | + VM_SHARED | VM_MAYSHARE)) == 0; +} + unsigned long mmap_region(struct file *file, unsigned long addr, unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) { @@ -1578,6 +1590,16 @@ unsigned long mmap_region(struct file *f } /* + * For anon mappings make sure we don't exceed the limit. + */ + if (anon_accountable_mapping(file, vm_flags)) { + unsigned long lim = rlimit(RLIMIT_DATA) >> PAGE_SHIFT; + + if (lim < (mm->anon_vm + (len >> PAGE_SHIFT))) + return -ENOMEM; + } + + /* * Can we just expand an old mapping? */ vma = vma_merge(mm, prev, addr, addr + len, vm_flags, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
