This patch fixes 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_DATA check (limit actually in bytes, not pages) and by default turns it into warning which prints at first VmData misuse. Like: "VmData 516096 exceeds RLIMIT_DATA 512000" 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". Signed-off-by: Konstantin Khlebnikov <koc...@gmail.com> Link: http://lkml.kernel.org/r/20151228211015.GL2194@uranus Reported-by: Christian Borntraeger <borntrae...@de.ibm.com> --- Documentation/kernel-parameters.txt | 5 +++++ mm/mmap.c | 12 +++++++++--- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index cfb2c0f1a4a8..d728caf7aa52 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1461,6 +1461,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. could change it dynamically, usually by /sys/module/printk/parameters/ignore_loglevel. + ignore_rlimit_data + Ignore RLIMIT_DATA setting for private mappings, + print warning at first misuse. Could be changed by + /sys/module/kernel/parameters/ignore_rlimit_data. + ihash_entries= [KNL] Set number of hash buckets for inode cache. diff --git a/mm/mmap.c b/mm/mmap.c index 84b12624ceb0..46d2ed6cb0df 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 +2985,12 @@ 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 ((flags & (VM_WRITE | VM_SHARED | + (VM_STACK_FLAGS & (VM_GROWSUP | VM_GROWSDOWN)))) == VM_WRITE && + mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT && + !WARN_ONCE(ignore_rlimit_data, "VmData %lu exceeds RLIMIT_DATA %lu", + (mm->data_vm + npages)<<PAGE_SHIFT, rlimit(RLIMIT_DATA))) + return false; return true; }
