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authorKonstantin Khlebnikov <koct9i@gmail.com>2016-02-02 16:57:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-03 08:28:43 -0800
commitd977d56ce5b3e8842236f2f9e7483d4914c9592e (patch)
tree179e5850a0567927d38e34a96747d53415b535b3 /mm/mmap.c
parent4758e198ad3bcbc1c468e0632c53a63a7d201649 (diff)
downloadlwn-d977d56ce5b3e8842236f2f9e7483d4914c9592e.tar.gz
lwn-d977d56ce5b3e8842236f2f9e7483d4914c9592e.zip
mm: warn about VmData over RLIMIT_DATA
This patch provides a way of working around a slight regression introduced by commit 84638335900f ("mm: rework virtual memory accounting"). Before that commit RLIMIT_DATA have control only over size of the brk region. But that change have caused problems with all existing versions of valgrind, because it set RLIMIT_DATA to zero. This patch fixes rlimit check (limit actually in bytes, not pages) and by default turns it into warning which prints at first VmData misuse: "mmap: top (795): VmData 516096 exceed data ulimit 512000. Will be forbidden soon." Behavior is controlled by boot param ignore_rlimit_data=y/n and by sysfs /sys/module/kernel/parameters/ignore_rlimit_data. For now it set to "y". [akpm@linux-foundation.org: tweak kernel-parameters.txt text[ Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Link: http://lkml.kernel.org/r/20151228211015.GL2194@uranus Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kees Cook <keescook@google.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 84b12624ceb0..cfc0cdca421e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -42,6 +42,7 @@
#include <linux/memory.h>
#include <linux/printk.h>
#include <linux/userfaultfd_k.h>
+#include <linux/moduleparam.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -69,6 +70,8 @@ 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;
+core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma, struct vm_area_struct *prev,
@@ -2982,9 +2985,17 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
return false;
- if ((flags & (VM_WRITE | VM_SHARED | (VM_STACK_FLAGS &
- (VM_GROWSUP | VM_GROWSDOWN)))) == VM_WRITE)
- return mm->data_vm + npages <= rlimit(RLIMIT_DATA);
+ 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",
+ current->comm, current->pid,
+ (mm->data_vm + npages) << PAGE_SHIFT,
+ rlimit(RLIMIT_DATA));
+ else
+ return false;
+ }
return true;
}
@@ -2993,11 +3004,11 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
{
mm->total_vm += npages;
- if ((flags & (VM_EXEC | VM_WRITE)) == VM_EXEC)
+ if (is_exec_mapping(flags))
mm->exec_vm += npages;
- else if (flags & (VM_STACK_FLAGS & (VM_GROWSUP | VM_GROWSDOWN)))
+ else if (is_stack_mapping(flags))
mm->stack_vm += npages;
- else if ((flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
+ else if (is_data_mapping(flags))
mm->data_vm += npages;
}