Commit f4fcd558 authored May 20, 2016 by Konstantin Khlebnikov Committed by Linus Torvalds May 20, 2016

mm: enable RLIMIT_DATA by default with workaround for valgrind

Since commit 84638335 ("mm: rework virtual memory accounting")
RLIMIT_DATA limits both brk() and private mmap() but this's disabled by
default because of incompatibility with older versions of valgrind.

Valgrind always set limit to zero and fails if RLIMIT_DATA is enabled.
Fortunately it changes only rlim_cur and keeps rlim_max for reverting
limit back when needed.

This patch checks current usage also against rlim_max if rlim_cur is
zero.  This is safe because task anyway can increase rlim_cur up to
rlim_max.  Size of brk is still checked against rlim_cur, so this part
is completely compatible - zero rlim_cur forbids brk() but allows
private mmap().

Link: http://lkml.kernel.org/r/56A28613.5070104@de.ibm.com


Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d5957d2f

mm/mmap.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -66,7 +66,7 @@ const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
		int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
		#endif

		static bool ignore_rlimit_data = true;
		static bool ignore_rlimit_data;
		core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);

		static void unmap_region(struct mm_struct *mm,
		@@ -2886,14 +2886,18 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)

		if (is_data_mapping(flags) &&
		mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
		if (ignore_rlimit_data)
		pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Will be forbidden soon.\n",
		/* Workaround for Valgrind */
		if (rlimit(RLIMIT_DATA) == 0 &&
		mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
		return true;
		if (!ignore_rlimit_data) {
		pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
		current->comm, current->pid,
		(mm->data_vm + npages) << PAGE_SHIFT,
		rlimit(RLIMIT_DATA));
		else
		return false;
		}
		}

		return true;
		}

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