From owner-svn-src-head@freebsd.org Mon Mar 26 16:31:13 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id EF690F53259; Mon, 26 Mar 2018 16:31:12 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id A1F02858F8; Mon, 26 Mar 2018 16:31:12 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 9CCC7768C; Mon, 26 Mar 2018 16:31:12 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w2QGVCia092787; Mon, 26 Mar 2018 16:31:12 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w2QGVCll092785; Mon, 26 Mar 2018 16:31:12 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201803261631.w2QGVCll092785@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Mon, 26 Mar 2018 16:31:12 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r331557 - head/sys/vm X-SVN-Group: head X-SVN-Commit-Author: kib X-SVN-Commit-Paths: head/sys/vm X-SVN-Commit-Revision: 331557 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Mar 2018 16:31:13 -0000 Author: kib Date: Mon Mar 26 16:31:12 2018 New Revision: 331557 URL: https://svnweb.freebsd.org/changeset/base/331557 Log: Allow to specify for vm_fault_quick_hold_pages() that nofault mode should be honored. We must not sleep or acquire any MI VM locks if TDP_NOFAULTING is specified. On the other hand, there were some callers in the tree which set TDP_NOFAULTING for larger scope than needed, I fixed the code which I wrote, but I suspect that linuxkpi and out of tree drm drivers might abuse this still. So only enable the mode for vm_fault_quick_hold_pages() where vm_fault_hold() is not called when specifically asked by user. I decided to use vm_prot_t flag to not change KPI. Since number of flags in vm_prot_t is limited, I reused the same flag which was already consumed for vm_map_lookup(). Reported and tested by: pho (as part of the larger patch) Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D14825 Modified: head/sys/vm/vm.h head/sys/vm/vm_fault.c Modified: head/sys/vm/vm.h ============================================================================== --- head/sys/vm/vm.h Mon Mar 26 16:06:04 2018 (r331556) +++ head/sys/vm/vm.h Mon Mar 26 16:31:12 2018 (r331557) @@ -80,7 +80,9 @@ typedef u_char vm_prot_t; /* protection codes */ #define VM_PROT_WRITE ((vm_prot_t) 0x02) #define VM_PROT_EXECUTE ((vm_prot_t) 0x04) #define VM_PROT_COPY ((vm_prot_t) 0x08) /* copy-on-read */ -#define VM_PROT_FAULT_LOOKUP ((vm_prot_t) 0x010) +#define VM_PROT_PRIV_FLAG ((vm_prot_t) 0x10) +#define VM_PROT_FAULT_LOOKUP VM_PROT_PRIV_FLAG +#define VM_PROT_QUICK_NOFAULT VM_PROT_PRIV_FLAG /* same to save bits */ #define VM_PROT_ALL (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE) #define VM_PROT_RW (VM_PROT_READ|VM_PROT_WRITE) Modified: head/sys/vm/vm_fault.c ============================================================================== --- head/sys/vm/vm_fault.c Mon Mar 26 16:06:04 2018 (r331556) +++ head/sys/vm/vm_fault.c Mon Mar 26 16:31:12 2018 (r331557) @@ -1524,7 +1524,18 @@ vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t ad * page was mapped at the specified virtual address or that * mapping had insufficient permissions. Attempt to fault in * and hold these pages. + * + * If vm_fault_disable_pagefaults() was called, + * i.e., TDP_NOFAULTING is set, we must not sleep nor + * acquire MD VM locks, which means we must not call + * vm_fault_hold(). Some (out of tree) callers mark + * too wide a code area with vm_fault_disable_pagefaults() + * already, use the VM_PROT_QUICK_NOFAULT flag to request + * the proper behaviour explicitly. */ + if ((prot & VM_PROT_QUICK_NOFAULT) != 0 && + (curthread->td_pflags & TDP_NOFAULTING) != 0) + goto error; for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) if (*mp == NULL && vm_fault_hold(map, va, prot, VM_FAULT_NORMAL, mp) != KERN_SUCCESS)