https://bugs.kde.org/show_bug.cgi?id=357833
--- Comment #5 from Mark Wielaard <m...@redhat.com> ---
For reference here is the full commit explaining that previously the
RLIMIT_DATA value indeed was mostly harmless only affecting brk, but now
restricts any data area allocations:
commit 84638335900f1995495838fe1bd4870c43ec1f67
Author: Konstantin Khlebnikov <koc...@gmail.com>
AuthorDate: Thu Jan 14 15:22:07 2016 -0800
Commit: Linus Torvalds <torva...@linux-foundation.org>
CommitDate: Thu Jan 14 16:00:49 2016 -0800
mm: rework virtual memory accounting
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.
Linus suggested to convert RLIMIT_DATA rlimit into something suitable
for anonymous memory accounting. But in this patch we go further, and
the changes are bundled together as:
* keep vma counting if CONFIG_PROC_FS=n, will be used for limits
* replace mm->shared_vm with better defined mm->data_vm
* account anonymous executable areas as executable
* account file-backed growsdown/up areas as stack
* drop struct file* argument from vm_stat_account
* enforce RLIMIT_DATA for size of data areas
This way code looks cleaner: now code/stack/data classification depends
only on vm_flags state:
VM_EXEC & ~VM_WRITE -> code (VmExe + VmLib in proc)
VM_GROWSUP | VM_GROWSDOWN -> stack (VmStk)
VM_WRITE & ~VM_SHARED & !stack -> data (VmData)
The rest (VmSize - VmData - VmStk - VmExe - VmLib) could be called
"shared", but that might be strange beast like readonly-private or VM_IO
area.
- RLIMIT_AS limits whole address space "VmSize"
- RLIMIT_STACK limits stack "VmStk" (but each vma individually)
- RLIMIT_DATA now limits "VmData"
Signed-off-by: Konstantin Khlebnikov <koc...@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcu...@openvz.org>
Cc: Quentin Casasnovas <quentin.casasno...@oracle.com>
Cc: Vegard Nossum <vegard.nos...@oracle.com>
Acked-by: Linus Torvalds <torva...@linux-foundation.org>
Cc: Willy Tarreau <w...@1wt.eu>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Kees Cook <keesc...@google.com>
Cc: Vladimir Davydov <vdavy...@virtuozzo.com>
Cc: Pavel Emelyanov <xe...@virtuozzo.com>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
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