mm: enable RLIMIT_DATA by default with workaround for valgrind

Since commit 84638335900f ("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>

diff --git a/mm/mmap.c b/mm/mmap.c
index fba246b8f1a54bd61fa761451adb8e5fac85f421..b9274a0c82c936c27a0cafc5d4b3bf4f99ac2ec5 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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,
@@ -2886,13 +2886,17 @@ 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;