From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 2C8D31A01A9 for ; Wed, 30 Jul 2014 19:31:44 +1000 (EST) 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 19:31:42 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 802B7357804F for ; Wed, 30 Jul 2014 19:31:40 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s6U98dx953477602 for ; Wed, 30 Jul 2014 19:08:39 +1000 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s6U9VdMF031236 for ; Wed, 30 Jul 2014 19:31:39 +1000 From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v4 03/16] mm: Add helpers for locked_vm Date: Wed, 30 Jul 2014 19:31:22 +1000 Message-Id: <1406712695-9491-4-git-send-email-aik@ozlabs.ru> In-Reply-To: <1406712695-9491-1-git-send-email-aik@ozlabs.ru> References: <1406712695-9491-1-git-send-email-aik@ozlabs.ru> Cc: Alexey Kardashevskiy , Michael Ellerman , Paul Mackerras , Gavin Shan List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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