From: Ian Campbell <ian.campbell@citrix.com>
To: "Wei Liu" <wei.liu2@citrix.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Cc: ian.jackson@eu.citrix.com, xen-devel@lists.xen.org
Subject: Re: [PATCH XEN v8 24/29] tools/libs/call: linux: touch newly allocated pages after madvise lockdown
Date: Tue, 19 Jan 2016 15:03:31 +0000 [thread overview]
Message-ID: <1453215811.29930.78.camel@citrix.com> (raw)
In-Reply-To: <20160119145848.GJ1691@citrix.com>
On Tue, 2016-01-19 at 14:58 +0000, Wei Liu wrote:
> On Tue, Jan 19, 2016 at 03:54:54PM +0100, Roger Pau Monné wrote:
> > El 19/01/16 a les 14.24, Wei Liu ha escrit:
> > > On Fri, Jan 15, 2016 at 01:23:03PM +0000, Ian Campbell wrote:
> > > > This avoids a potential issue with a fork after allocation but
> > > > before
> > > > madvise.
> > > >
> > > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> > > > ---
> > > > v7: New, replacing "tools/libs/call: linux: avoid forking between
> > > > mmap
> > > > and madvise".
> > > > ---
> > > > tools/libs/call/linux.c | 14 +++++++++++++-
> > > > 1 file changed, 13 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/tools/libs/call/linux.c b/tools/libs/call/linux.c
> > > > index 3641e41..651f380 100644
> > > > --- a/tools/libs/call/linux.c
> > > > +++ b/tools/libs/call/linux.c
> > >
> > > I didn't notice you only handled this for Linux until now.
> > >
> > > I think FreeBSD and NetBSD need similar treatment, too? But then
> > > current
> > > BSD* code doesn't even support DONTFORK in madvise.
> > >
> > > Adding Roger for more input.
> >
> > Hm, right, thanks for noticing this. I don't think FreeBSD needs a
> > similar treatment (pre-faulting), because mlock will remove any CoW
> > when
> > making the pages wired.
> >
> > Also, AFAICT we don't need to call madvise or minherit(2) because
> > mlock(2) already takes care of preventing the memory region from being
> > copied to the child on fork:
> >
> > "Locked mappings are not inherited by the child process after a
> > fork(2)." [0]
> >
> > So I think we are safe on the FreeBSD side.
> >
>
> But what if the process forks between mmap and mlock? I think that
> warrants touching the area like we do for Linux here.
mlock guarantees the memory is populated, I think, which is equivalent to
touching it.
On Linux we use madvise not mlock, which doesn't make the same claims.
>
Ian.
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next prev parent reply other threads:[~2016-01-19 15:03 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1452864168.32341.97.camel@citrix.com>
2016-01-15 13:22 ` [PATCH XEN v8 00/29] Begin to disentangle libxenctrl and provide some stable libraries Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 01/29] tools/libxc: Remove osdep indirection for xc_evtchn Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 02/29] tools: Refactor /dev/xen/evtchn wrappers into libxenevtchn Ian Campbell
2016-01-22 11:48 ` Ian Campbell
2016-01-22 17:12 ` Boris Ostrovsky
2016-01-25 9:48 ` Ian Campbell
2016-01-25 14:35 ` Ian Jackson
2016-01-25 14:39 ` Boris Ostrovsky
2016-01-25 14:47 ` Ian Campbell
2016-01-25 14:49 ` Andrew Cooper
2016-01-25 15:28 ` Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 03/29] tools: Arrange to check public headers for ANSI compatiblity Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 04/29] tools/libxc: Remove osdep indirection for xc_gnt{shr, tab} Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 05/29] tools: Refactor /dev/xen/gnt{dev, shr} wrappers into libxengnttab Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 06/29] tools/libxc: Remove osdep indirection for privcmd Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 07/29] tools: Refactor hypercall calling wrappers into libxencall Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 08/29] tools/libxc: drop xc_map_foreign_bulk_compat wrappers Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 09/29] tools: Remove xc_map_foreign_batch Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 10/29] tools: Implement xc_map_foreign_range(s) in terms of common helper Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 11/29] tools: Refactor foreign memory mapping into libxenforeignmemory Ian Campbell
2016-01-25 12:01 ` Olaf Hering
2016-01-25 12:31 ` Ian Campbell
2016-01-25 12:44 ` Ian Campbell
2016-01-25 12:45 ` [PATCH] kdd: Opt in to libxc compat xc_map_foreign_* intefaces Ian Campbell
2016-01-25 13:25 ` Tim Deegan
2016-01-25 14:22 ` Ian Campbell
2016-01-25 14:00 ` Olaf Hering
2016-01-25 13:18 ` [PATCH] kdd: build using Werror Ian Campbell
2016-01-25 13:20 ` Olaf Hering
2016-01-25 13:24 ` Ian Campbell
2016-01-25 13:25 ` Tim Deegan
2016-01-25 14:22 ` Ian Campbell
2016-01-25 14:37 ` Olaf Hering
2016-01-15 13:22 ` [PATCH XEN v8 12/29] tools/libs/foreignmemory: provide xenforeignmemory_unmap Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 13/29] tools/libs/foreignmemory: use size_t for size arguments Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 14/29] tools/libs/foreignmemory: Mention restrictions on fork in docs Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-19 13:34 ` Ian Campbell
2016-01-19 14:25 ` Wei Liu
2016-01-15 13:22 ` [PATCH XEN v8 15/29] tools/libs/foreignmemory: Support err == NULL to map Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 16/29] tools/libs/foreignmemory: pull array length argument to map forward Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 17/29] tools/libs/evtchn: Review and update doc comments Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 18/29] tools/libs/evtchn: Use uint32_t for domid arguments Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-15 13:22 ` [PATCH XEN v8 19/29] tools/libs: Clean up hard tabs Ian Campbell
2016-01-15 13:22 ` [PATCH XEN v8 20/29] tools/libs/gnttab: Extensive updates to API documentation Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-15 13:23 ` [PATCH XEN v8 21/29] tools/libs/call: Update some log messages to not refer to xc Ian Campbell
2016-01-15 13:23 ` [PATCH XEN v8 22/29] tools/libs/call: Describe return values and error semantics for xencall* Ian Campbell
2016-01-15 13:23 ` [PATCH XEN v8 23/29] tools/libs/call: Avoid xc_memalign in netbsd and solaris backends Ian Campbell
2016-01-15 13:23 ` [PATCH XEN v8 24/29] tools/libs/call: linux: touch newly allocated pages after madvise lockdown Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-19 13:40 ` Ian Campbell
2016-01-19 14:26 ` Wei Liu
2016-01-19 14:54 ` Roger Pau Monné
2016-01-19 14:58 ` Wei Liu
2016-01-19 15:03 ` Ian Campbell [this message]
2016-01-19 15:49 ` Wei Liu
2016-01-19 15:59 ` Ian Campbell
2016-01-15 13:23 ` [PATCH XEN v8 25/29] tools/libs/{call, evtchn}: Document requirements around forking Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-15 13:23 ` [PATCH XEN v8 26/29] tools/libs/*: Use O_CLOEXEC on Linux and FreeBSD Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-15 13:23 ` [PATCH XEN v8 27/29] tools: Update CFLAGS for qemu-xen to allow it to use new libraries Ian Campbell
2016-01-15 13:23 ` [PATCH XEN v8 28/29] tools/libs/*: Introduce APIs to restrict handles to a specific domain Ian Campbell
2016-01-19 13:24 ` Wei Liu
2016-01-19 13:44 ` Ian Campbell
2016-01-19 14:30 ` Wei Liu
2016-01-15 13:23 ` [PATCH XEN v8 29/29] HACK: Update Config.mk to pull all the right bits from my xenbits trees Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 0/8] Begin to disentangle libxenctrl and provide some stable libraries Ian Campbell
[not found] ` <1452864224-2554-1-git-send-email-ian.campbell@citrix.com>
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 1/8] xen_console: correctly cleanup primary console on teardown Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 2/8] xen: Switch to libxenevtchn interface for compat shims Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 3/8] xen: Switch to libxengnttab " Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 5/8] xen: Switch uses of xc_map_foreign_{pages, bulk} to use libxenforeignmemory API Ian Campbell
2016-01-15 14:43 ` Stefano Stabellini
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 6/8] xen: Use stable library interfaces when they are available Ian Campbell
2016-01-15 14:43 ` Stefano Stabellini
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 7/8] xen: domainbuild: reopen libxenctrl interface after forking for domain watcher Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN v8 8/8] xen: make it possible to build without the Xen PV domain builder Ian Campbell
2016-01-15 14:44 ` [PATCH QEMU-XEN v8 0/8] Begin to disentangle libxenctrl and provide some stable libraries Stefano Stabellini
[not found] ` <alpine.DEB.2.02.1601151443370.16178@kaball.uk.xensource.com>
2016-01-15 15:08 ` Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN-TRADITIONAL v8 0/4] " Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN-TRADITIONAL v8 1/4] qemu-xen-traditional: Use libxenevtchn Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN-TRADITIONAL v8 2/4] qemu-xen-traditional: Use libxengnttab Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN-TRADITIONAL v8 3/4] qemu-xen-traditional: Add libxencall to rpath-link Ian Campbell
2016-01-15 13:23 ` [PATCH QEMU-XEN-TRADITIONAL v8 4/4] qemu-xen-traditional: Add libxenforeignmemory " Ian Campbell
2016-01-15 13:23 ` [PATCH MINI-OS v8 0/4] Begin to disentangle libxenctrl and provide some stable libraries Ian Campbell
2016-01-15 13:24 ` [PATCH MINI-OS v8 1/4] mini-os: Include libxenevtchn with libxc Ian Campbell
2016-01-15 13:24 ` [PATCH MINI-OS v8 2/4] mini-os: Include libxengnttab " Ian Campbell
2016-01-15 13:24 ` [PATCH MINI-OS v8 3/4] mini-os: Include libxencall " Ian Campbell
2016-01-15 13:24 ` [PATCH MINI-OS v8 4/4] mini-os: Include libxenforeignmemory " Ian Campbell
2016-01-19 15:44 ` [Minios-devel] [PATCH v8 0/<VARIOUS>] Begin to disentangle libxenctrl and provide some stable libraries Ian Campbell
[not found] ` <1453218278.29930.89.camel@citrix.com>
2016-01-22 10:42 ` Ian Campbell
2016-01-22 14:14 ` Ian Campbell
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