linux-kernel - [PATCH] mm: Always print RLIMIT

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Date:   Tue,  6 Feb 2018 16:45:05 +0000
From:   David Woodhouse <dwmw@...zon.co.uk>
To:     Konstantin Khlebnikov <koct9i@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Vladimir Davydov <vdavydov@...tuozzo.com>,
        Andy Lutomirski <luto@...capital.net>,
        Quentin Casasnovas <quentin.casasnovas@...cle.com>,
        Kees Cook <keescook@...gle.com>, Willy Tarreau <w@....eu>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Laura Abbott <labbott@...hat.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] mm: Always print RLIMIT_DATA warning

The documentation for ignore_rlimit_data says that it will print a warning
at first misuse. Yet it doesn't seem to do that. Fix the code to print
the warning even when we allow the process to continue.

Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
---
We should probably also do what Linus suggested in 
https://lkml.org/lkml/2016/9/16/585

 mm/mmap.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 9efdc021..dd76ea3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3184,13 +3184,15 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
 		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));
+
+		pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
+			     current->comm, current->pid,
+			     (mm->data_vm + npages) << PAGE_SHIFT,
+			     rlimit(RLIMIT_DATA),
+			     ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
+
+		if (!ignore_rlimit_data)
 			return false;
-		}
 	}
 
 	return true;
-- 
2.7.4