From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id 16C906B0038 for ; Wed, 30 Jul 2014 05:28:35 -0400 (EDT) Received: by mail-pd0-f173.google.com with SMTP id w10so1159210pde.18 for ; Wed, 30 Jul 2014 02:28:34 -0700 (PDT) Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com. [202.81.31.143]) by mx.google.com with ESMTPS id 4si864983pdm.284.2014.07.30.02.28.32 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 30 Jul 2014 02:28:33 -0700 (PDT) Received: from /spool/local by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 30 Jul 2014 19:28:29 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 78B23357804F for ; Wed, 30 Jul 2014 19:28:22 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s6U95KmE62521492 for ; Wed, 30 Jul 2014 19:05:22 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s6U9SJoX021411 for ; Wed, 30 Jul 2014 19:28:20 +1000 From: Alexey Kardashevskiy Subject: [RFC PATCH] mm: Add helpers for locked_vm Date: Wed, 30 Jul 2014 19:28:13 +1000 Message-Id: <1406712493-9284-1-git-send-email-aik@ozlabs.ru> Sender: owner-linux-mm@kvack.org List-ID: To: Alexey Kardashevskiy Cc: Benjamin Herrenschmidt , Andrew Morton , "Kirill A . Shutemov" , Rik van Riel , Peter Zijlstra , Mel Gorman , Johannes Weiner , Andrea Arcangeli , Sasha Levin , Wanpeng Li , Vlastimil Babka , =?UTF-8?q?J=C3=B6rn=20Engel?= , "Paul E . McKenney" , Davidlohr Bueso , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alex Williamson , Alexander Graf , Michael Ellerman This adds 2 helpers to change the locked_vm counter: - try_increase_locked_vm - may fail if new locked_vm value will be greater than the RLIMIT_MEMLOCK limit; - decrease_locked_vm. These will be used by drivers capable of locking memory by userspace request. For example, VFIO can use it to check if it can lock DMA memory or PPC-KVM can use it to check if it can lock memory for TCE tables. Signed-off-by: Alexey Kardashevskiy --- include/linux/mm.h | 3 +++ mm/mlock.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 52 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index e03dd29..1cb219d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2113,5 +2113,8 @@ void __init setup_nr_node_ids(void); static inline void setup_nr_node_ids(void) {} #endif +extern long try_increment_locked_vm(long npages); +extern void decrement_locked_vm(long npages); + #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ diff --git a/mm/mlock.c b/mm/mlock.c index b1eb536..39e4b55 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -864,3 +864,52 @@ void user_shm_unlock(size_t size, struct user_struct *user) spin_unlock(&shmlock_user_lock); free_uid(user); } + +/** + * try_increment_locked_vm() - checks if new locked_vm value is going to + * be less than RLIMIT_MEMLOCK and increments it by npages if it is. + * + * @npages: the number of pages to add to locked_vm. + * + * Returns 0 if succeeded or negative value if failed. + */ +long try_increment_locked_vm(long npages) +{ + long ret = 0, locked, lock_limit; + + if (!current || !current->mm) + return -ESRCH; /* process exited */ + + down_write(¤t->mm->mmap_sem); + locked = current->mm->locked_vm + npages; + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) { + pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n", + rlimit(RLIMIT_MEMLOCK)); + ret = -ENOMEM; + } else { + current->mm->locked_vm += npages; + } + up_write(¤t->mm->mmap_sem); + + return ret; +} +EXPORT_SYMBOL_GPL(try_increment_locked_vm); + +/** + * decrement_locked_vm() - decrements the current task's locked_vm counter. + * + * @npages: the number to decrement by. + */ +void decrement_locked_vm(long npages) +{ + if (!current || !current->mm) + return; /* process exited */ + + down_write(¤t->mm->mmap_sem); + if (npages > current->mm->locked_vm) + npages = current->mm->locked_vm; + current->mm->locked_vm -= npages; + up_write(¤t->mm->mmap_sem); +} +EXPORT_SYMBOL_GPL(decrement_locked_vm); -- 2.0.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org