Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751984AbaG3J2f (ORCPT ); Wed, 30 Jul 2014 05:28:35 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:57751 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999AbaG3J2d (ORCPT ); Wed, 30 Jul 2014 05:28:33 -0400 From: Alexey Kardashevskiy 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 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> X-Mailer: git-send-email 2.0.0 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14073009-3568-0000-0000-000005FC6226 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/