* Re: [PATCH v4 1/2] capabilities: Ambient capabilities
From: Andrew Morton @ 2015-07-17 20:50 UTC (permalink / raw)
To: Christoph Lameter
Cc: Andy Lutomirski, James Morris, Andy Lutomirski, Andrew Morton,
Serge E. Hallyn, Serge Hallyn, James Morris, Jarkko Sakkinen,
Ted Ts'o, Andrew G. Morgan, Linux API, Mimi Zohar,
Michael Kerrisk, Austin S Hemmelgarn, linux-security-module,
Aaron Jones, Serge Hallyn, LKML, Markku Savela, Kees Cook,
Jonathan Corbet
In-Reply-To: <alpine.DEB.2.11.1507171539590.13763-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
On Fri, 17 Jul 2015 15:40:57 -0500 (CDT) Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org> wrote:
> Here is a test program that can be used to verify the functionality.
I slurped that into the changelog.
Adding a selftest into tools/testing/selftests/ would be appropriate.
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Ondřej Bílka @ 2015-07-17 22:43 UTC (permalink / raw)
To: Mathieu Desnoyers
Cc: Ben Maurer, Paul Turner, Andrew Hunter, Peter Zijlstra,
Ingo Molnar, rostedt, Paul E. McKenney, Josh Triplett,
Lai Jiangshan, Linus Torvalds, Andrew Morton, linux-api,
libc-alpha
In-Reply-To: <626545401.1010.1437149010438.JavaMail.zimbra-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>
On Fri, Jul 17, 2015 at 04:03:30PM +0000, Mathieu Desnoyers wrote:
> ----- On Jul 17, 2015, at 6:58 AM, Ondřej Bílka neleai@seznam.cz wrote:
> [...]
> >> If we invoke this per-thread registration directly in the glibc NPTL
> >> implementation,
> >> in start_thread, do you think it would fit your requirements ?
> >>
> > A generic solution would be adding eager initialization of thread_local
> > variables which would fix more performance problems.
>
> Concretely, what code would be in charge of this initialization ?
>
> What changes does "eager initialization" imply from the current
> implementation ?
>
Now if you write
class foo{
public:
foo(){
printf("init\n");
}
foo(const foo &x){
printf("init\n");
}
int bar()
{
return 32;
}
};
thread_local class foo x;
Then constructor isn't called in all threads, only main as its lazily
initialized. You need to call x.bar() in each thread to cause
initialization.
> > Second would be write patch to libc adding function
> > pthread_create_add_hook_np to register function that would be ran after
> > each thread creation.
>
> Do you suggest that this callback should be registered once per thread,
> or somehow attached to pthread_attr_t ? As maintainer of lttng-ust,
> where we need some control over our own threads, but where we want minimal
> impact on the overall application, I would really prefer if we can attach
> the callback to pthread_attr_t.
>
Could you elaborate. I was suggesting per-thread callback, what do you
want to do with pthread_attr_t?
^ permalink raw reply
* Re: [PATCH v4 1/2] capabilities: Ambient capabilities
From: Kees Cook @ 2015-07-17 23:10 UTC (permalink / raw)
To: Andrew Morton
Cc: Christoph Lameter, Andy Lutomirski, James Morris, Andy Lutomirski,
Andrew Morton, Serge E. Hallyn, Serge Hallyn, James Morris,
Jarkko Sakkinen, Ted Ts'o, Andrew G. Morgan, Linux API,
Mimi Zohar, Michael Kerrisk, Austin S Hemmelgarn,
linux-security-module, Aaron Jones, Serge Hallyn, LKML,
Markku Savela, Jonathan Corbet
In-Reply-To: <20150717135057.8e09390f1c10bc11d10a42f5@linux-foundation.org>
On Fri, Jul 17, 2015 at 1:50 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Fri, 17 Jul 2015 15:40:57 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote:
>
>> Here is a test program that can be used to verify the functionality.
>
> I slurped that into the changelog.
>
> Adding a selftest into tools/testing/selftests/ would be appropriate.
Yes please! I'd love to see a general privilege transition testing
area. But starting with just this would be fine. :)
-Kees
--
Kees Cook
Chrome OS Security
^ permalink raw reply
* Re: [PATCH v4 1/2] capabilities: Ambient capabilities
From: Andy Lutomirski @ 2015-07-17 23:21 UTC (permalink / raw)
To: Kees Cook
Cc: Andrew Morton, Christoph Lameter, James Morris, Andy Lutomirski,
Andrew Morton, Serge E. Hallyn, Serge Hallyn, James Morris,
Jarkko Sakkinen, Ted Ts'o, Andrew G. Morgan, Linux API,
Mimi Zohar, Michael Kerrisk, Austin S Hemmelgarn,
linux-security-module, Aaron Jones, Serge Hallyn, LKML,
Markku Savela, Jonathan Corbet
In-Reply-To: <CAGXu5j+V0fMae5OOHwU5DcMrG0TCANYOTfbz5+LDZZqYKcXAaw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Fri, Jul 17, 2015 at 4:10 PM, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
> On Fri, Jul 17, 2015 at 1:50 PM, Andrew Morton
> <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> wrote:
>> On Fri, 17 Jul 2015 15:40:57 -0500 (CDT) Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org> wrote:
>>
>>> Here is a test program that can be used to verify the functionality.
>>
>> I slurped that into the changelog.
>>
>> Adding a selftest into tools/testing/selftests/ would be appropriate.
>
> Yes please! I'd love to see a general privilege transition testing
> area. But starting with just this would be fine. :)
I'll try to write something soonish. Might be a little while. Plate
is currently full with non-Linux work and a handful of
much-more-urgent Linux things.
--Andy
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Ondřej Bílka @ 2015-07-17 23:28 UTC (permalink / raw)
To: Linus Torvalds
Cc: Andy Lutomirski, Mathieu Desnoyers, Ben Maurer, Paul Turner,
Andrew Hunter, Peter Zijlstra, Ingo Molnar, rostedt,
Paul E. McKenney, Josh Triplett, Lai Jiangshan, Andrew Morton,
linux-api, libc-alpha
In-Reply-To: <CA+55aFz-VBnEKh0SPKgu8xV5=Zb+=6odybVUDoOYOknshbcFJA@mail.gmail.com>
On Fri, Jul 17, 2015 at 11:48:14AM -0700, Linus Torvalds wrote:
> On Thu, Jul 16, 2015 at 12:27 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> >
> > If we actually bit the bullet and implemented per-cpu mappings
>
> That's not ever going to happen.
>
> The Linux VM model of "one page table per VM" is the right one.
> Anything else sucks, and makes threading a disaster.
>
> So you can try to prove me wrong, but seriously, I doubt you'll succeed.
>
> On x86, if you want per-cpu memory areas, you should basically plan on
> using segment registers instead (although other odd state has been
> used - there's been the people who use segment limits etc rather than
> the *pointer* itself, preferring to use "lsl" to get percpu data. You
> could also imaging hiding things in the vector state somewhere if you
> control your environment well enough).
>
Thats correct, problem is that you need some sort of hack like this on
archs that otherwise would need syscall to get tid/access tls variable.
On x64 and archs that have register for tls this could be implemented
relatively easily.
Kernel needs to allocate
int running_cpu_for_tid[32768];
On context switch it atomically writes to this table
running_cpu_for_tid[tid] = cpu;
This table is read-only accessible from userspace as mmaped file.
Then userspace just needs to access it with three indirections like:
__thread tid;
char caches[CPU_MAX];
#define getcpu_cache caches[tid > 32768 ? get_cpu() : running_cpu_for_tid[tid]]
With more complicated kernel interface you could eliminate one
indirection as we would use void * array instead and thread could do
syscall to register what values it should use for each thread.
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Andy Lutomirski @ 2015-07-17 23:33 UTC (permalink / raw)
To: Ondřej Bílka
Cc: Linus Torvalds, Mathieu Desnoyers, Ben Maurer, Paul Turner,
Andrew Hunter, Peter Zijlstra, Ingo Molnar, rostedt,
Paul E. McKenney, Josh Triplett, Lai Jiangshan, Andrew Morton,
linux-api, libc-alpha
In-Reply-To: <20150717232836.GA13604@domone>
On Fri, Jul 17, 2015 at 4:28 PM, Ondřej Bílka <neleai@seznam.cz> wrote:
> On Fri, Jul 17, 2015 at 11:48:14AM -0700, Linus Torvalds wrote:
>>
>> On x86, if you want per-cpu memory areas, you should basically plan on
>> using segment registers instead (although other odd state has been
>> used - there's been the people who use segment limits etc rather than
>> the *pointer* itself, preferring to use "lsl" to get percpu data. You
>> could also imaging hiding things in the vector state somewhere if you
>> control your environment well enough).
>>
> Thats correct, problem is that you need some sort of hack like this on
> archs that otherwise would need syscall to get tid/access tls variable.
>
> On x64 and archs that have register for tls this could be implemented
> relatively easily.
>
> Kernel needs to allocate
>
> int running_cpu_for_tid[32768];
>
> On context switch it atomically writes to this table
>
> running_cpu_for_tid[tid] = cpu;
>
> This table is read-only accessible from userspace as mmaped file.
>
> Then userspace just needs to access it with three indirections like:
>
> __thread tid;
>
> char caches[CPU_MAX];
> #define getcpu_cache caches[tid > 32768 ? get_cpu() : running_cpu_for_tid[tid]]
>
> With more complicated kernel interface you could eliminate one
> indirection as we would use void * array instead and thread could do
> syscall to register what values it should use for each thread.
Or we implement per-cpu segment registers so you can point gs directly
at percpu data. This is conceptually easy and has no weird ABI
issues. All it needs is an implementation and some good tests.
I think the API should be "set gsbase to x + y*(cpu number)". On
x86_64, userspace just allocates a big swath of virtual space and
populates it as needed.
--Andy
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Mathieu Desnoyers @ 2015-07-18 2:43 UTC (permalink / raw)
To: Ondřej Bílka
Cc: Ben Maurer, Paul Turner, Andrew Hunter, Peter Zijlstra,
Ingo Molnar, rostedt, Paul E. McKenney, Josh Triplett,
Lai Jiangshan, Linus Torvalds, Andrew Morton, linux-api,
libc-alpha
In-Reply-To: <20150717224353.GA7150@domone>
----- On Jul 17, 2015, at 6:43 PM, Ondřej Bílka neleai@seznam.cz wrote:
> On Fri, Jul 17, 2015 at 04:03:30PM +0000, Mathieu Desnoyers wrote:
>> ----- On Jul 17, 2015, at 6:58 AM, Ondřej Bílka neleai@seznam.cz wrote:
>> [...]
>> >> If we invoke this per-thread registration directly in the glibc NPTL
>> >> implementation,
>> >> in start_thread, do you think it would fit your requirements ?
>> >>
>
[...]
>> > Second would be write patch to libc adding function
>> > pthread_create_add_hook_np to register function that would be ran after
>> > each thread creation.
>>
>> Do you suggest that this callback should be registered once per thread,
>> or somehow attached to pthread_attr_t ? As maintainer of lttng-ust,
>> where we need some control over our own threads, but where we want minimal
>> impact on the overall application, I would really prefer if we can attach
>> the callback to pthread_attr_t.
>>
> Could you elaborate. I was suggesting per-thread callback, what do you
> want to do with pthread_attr_t?
Hrm, nevermind, even in the context of lttng-ust, I'd want the callback to
be called for every thread in the application. Therefore, registering this
callback once per process seems to make sense.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Rich Felker @ 2015-07-18 7:34 UTC (permalink / raw)
To: Ondřej Bílka
Cc: Linus Torvalds, Andy Lutomirski, Mathieu Desnoyers, Ben Maurer,
Paul Turner, Andrew Hunter, Peter Zijlstra, Ingo Molnar, rostedt,
Paul E. McKenney, Josh Triplett, Lai Jiangshan, Andrew Morton,
linux-api, libc-alpha
In-Reply-To: <20150717232836.GA13604@domone>
On Sat, Jul 18, 2015 at 01:28:36AM +0200, Ondřej Bílka wrote:
> On Fri, Jul 17, 2015 at 11:48:14AM -0700, Linus Torvalds wrote:
> > On Thu, Jul 16, 2015 at 12:27 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> > >
> > > If we actually bit the bullet and implemented per-cpu mappings
> >
> > That's not ever going to happen.
> >
> > The Linux VM model of "one page table per VM" is the right one.
> > Anything else sucks, and makes threading a disaster.
> >
> > So you can try to prove me wrong, but seriously, I doubt you'll succeed.
> >
> > On x86, if you want per-cpu memory areas, you should basically plan on
> > using segment registers instead (although other odd state has been
> > used - there's been the people who use segment limits etc rather than
> > the *pointer* itself, preferring to use "lsl" to get percpu data. You
> > could also imaging hiding things in the vector state somewhere if you
> > control your environment well enough).
> >
> Thats correct, problem is that you need some sort of hack like this on
> archs that otherwise would need syscall to get tid/access tls variable.
>
> On x64 and archs that have register for tls this could be implemented
> relatively easily.
>
> Kernel needs to allocate
>
> int running_cpu_for_tid[32768];
This does not scale. You're assuming the default task ("pid") number
limit, but this can be raised up to 512k (beyond that is impossible
because of PI/robust futex ABI).
> On context switch it atomically writes to this table
>
> running_cpu_for_tid[tid] = cpu;
>
> This table is read-only accessible from userspace as mmaped file.
There is a much simpler solution: use a per-cpu (rather than per-task)
page that contains the right value for the cpu. I believe vdso already
does something like this, no?
Rich
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Florian Weimer @ 2015-07-18 9:47 UTC (permalink / raw)
To: Mathieu Desnoyers
Cc: Ben Maurer, Paul Turner, Andrew Hunter, Peter Zijlstra,
Ingo Molnar, rostedt, Paul E. McKenney, Josh Triplett,
Lai Jiangshan, Linus Torvalds, Andrew Morton, linux-api,
libc-alpha
In-Reply-To: <549319255.383.1437070088597.JavaMail.zimbra@efficios.com>
* Mathieu Desnoyers:
> The related question then becomes: should we issue this system call once
> per process, or once per thread at thread creation ? Issuing it once per
> thread is marginally more costly for thread creation, but seems to be
> easier to deal with internally within the kernel.
I might be missing something, but here is my take:
It has to be a per-thread attribute because glibc uses clone
internally and wants to set the flag, but the same process may have
application or library code which uses clone to create threads, too,
but does not know about this new feature. If it's per-process, the
existing code would fail.
(We may argue indefinitely if this is a supported use case from the
glibc point of view, but I'm pretty sure there is code out there which
does exactly this, even though it's fairly complicated to get right.)
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Ondřej Bílka @ 2015-07-18 10:35 UTC (permalink / raw)
To: Andy Lutomirski
Cc: Linus Torvalds, Mathieu Desnoyers, Ben Maurer, Paul Turner,
Andrew Hunter, Peter Zijlstra, Ingo Molnar, rostedt,
Paul E. McKenney, Josh Triplett, Lai Jiangshan, Andrew Morton,
linux-api, libc-alpha
In-Reply-To: <CALCETrVY=kjeA_4pazy3BL+ekfcV6WHKw8e3z-LBxx_uP1bw2Q@mail.gmail.com>
On Fri, Jul 17, 2015 at 04:33:42PM -0700, Andy Lutomirski wrote:
> On Fri, Jul 17, 2015 at 4:28 PM, Ondřej Bílka <neleai@seznam.cz> wrote:
> > On Fri, Jul 17, 2015 at 11:48:14AM -0700, Linus Torvalds wrote:
> >>
> >> On x86, if you want per-cpu memory areas, you should basically plan on
> >> using segment registers instead (although other odd state has been
> >> used - there's been the people who use segment limits etc rather than
> >> the *pointer* itself, preferring to use "lsl" to get percpu data. You
> >> could also imaging hiding things in the vector state somewhere if you
> >> control your environment well enough).
> >>
> > Thats correct, problem is that you need some sort of hack like this on
> > archs that otherwise would need syscall to get tid/access tls variable.
> >
> > On x64 and archs that have register for tls this could be implemented
> > relatively easily.
> >
> > Kernel needs to allocate
> >
> > int running_cpu_for_tid[32768];
> >
> > On context switch it atomically writes to this table
> >
> > running_cpu_for_tid[tid] = cpu;
> >
> > This table is read-only accessible from userspace as mmaped file.
> >
> > Then userspace just needs to access it with three indirections like:
> >
> > __thread tid;
> >
> > char caches[CPU_MAX];
> > #define getcpu_cache caches[tid > 32768 ? get_cpu() : running_cpu_for_tid[tid]]
> >
> > With more complicated kernel interface you could eliminate one
> > indirection as we would use void * array instead and thread could do
> > syscall to register what values it should use for each thread.
>
> Or we implement per-cpu segment registers so you can point gs directly
> at percpu data. This is conceptually easy and has no weird ABI
> issues. All it needs is an implementation and some good tests.
>
That only works if you have free register on your arch. As gs there was
rfc to teach gcc use it which could give bigger speedup. I didn't see
how much this could help yet so I am bit skeptical.
> I think the API should be "set gsbase to x + y*(cpu number)". On
> x86_64, userspace just allocates a big swath of virtual space and
> populates it as needed.
>
That wouldn't work well if two shared libraries want to use that. You
would need to use something like se it to 4096*cpu_number or so.
Also we didn't considered yet overhead, as this slows down everything a
bit due slower context switches. So will this needs to have widespread
performance improvement to be worthwhile. What are use cases to make
that pay itself?
^ permalink raw reply
* Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)
From: Ondřej Bílka @ 2015-07-18 10:51 UTC (permalink / raw)
To: Rich Felker
Cc: Linus Torvalds, Andy Lutomirski, Mathieu Desnoyers, Ben Maurer,
Paul Turner, Andrew Hunter, Peter Zijlstra, Ingo Molnar, rostedt,
Paul E. McKenney, Josh Triplett, Lai Jiangshan, Andrew Morton,
linux-api, libc-alpha
In-Reply-To: <20150718073433.GH1173-C3MtFaGISjmo6RMmaWD+6Sb1p8zYI1N1@public.gmane.org>
On Sat, Jul 18, 2015 at 03:34:33AM -0400, Rich Felker wrote:
> On Sat, Jul 18, 2015 at 01:28:36AM +0200, Ondřej Bílka wrote:
> > On Fri, Jul 17, 2015 at 11:48:14AM -0700, Linus Torvalds wrote:
> > > On Thu, Jul 16, 2015 at 12:27 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> > > >
> > > > If we actually bit the bullet and implemented per-cpu mappings
> > >
> > > That's not ever going to happen.
> > >
> > > The Linux VM model of "one page table per VM" is the right one.
> > > Anything else sucks, and makes threading a disaster.
> > >
> > > So you can try to prove me wrong, but seriously, I doubt you'll succeed.
> > >
> > > On x86, if you want per-cpu memory areas, you should basically plan on
> > > using segment registers instead (although other odd state has been
> > > used - there's been the people who use segment limits etc rather than
> > > the *pointer* itself, preferring to use "lsl" to get percpu data. You
> > > could also imaging hiding things in the vector state somewhere if you
> > > control your environment well enough).
> > >
> > Thats correct, problem is that you need some sort of hack like this on
> > archs that otherwise would need syscall to get tid/access tls variable.
> >
> > On x64 and archs that have register for tls this could be implemented
> > relatively easily.
> >
> > Kernel needs to allocate
> >
> > int running_cpu_for_tid[32768];
>
> This does not scale. You're assuming the default task ("pid") number
> limit, but this can be raised up to 512k (beyond that is impossible
> because of PI/robust futex ABI).
>
Doesn't matter much, you will allocate 512k instead. As scaling if you
have simultaneously more than 32k threads running you have different
worries than how slow its to get cpu id.
> > On context switch it atomically writes to this table
> >
> > running_cpu_for_tid[tid] = cpu;
> >
> > This table is read-only accessible from userspace as mmaped file.
>
> There is a much simpler solution: use a per-cpu (rather than per-task)
> page that contains the right value for the cpu. I believe vdso already
> does something like this, no?
>
Thats exactly what I suggested before to improve tls when you don't have
register for that.
If thats already done its just matter of abi for kernel map per-cpu page
to fixed virtual page and save/restore tcb in same way as it sets cpuid.
With that abi a tls access would cost just extra load more than of static
variable.
^ permalink raw reply
* RE: [PATCH 3/3] hpsa: Convert DEVICE_ATTR macro usage to DEVICE_ATTR_RO|WR|WO
From: Don Brace @ 2015-07-18 16:21 UTC (permalink / raw)
To: Seymour, Shane M, linux-scsi@vger.kernel.org,
James Bottomley (JBottomley@Odin.com), ISS StorageDev
Cc: linux-api@vger.kernel.org,
Greg KH <greg@kroah.com> (greg@kroah.com)
In-Reply-To: <DDB9C85B850785449757F9914A034FCB4442E19F@G9W0766.americas.hpqcorp.net>
> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Seymour, Shane M
> Sent: Tuesday, June 30, 2015 10:47 PM
> To: linux-scsi@vger.kernel.org; James Bottomley (JBottomley@Odin.com); ISS
> StorageDev
> Cc: linux-api@vger.kernel.org; Greg KH <greg@kroah.com> (greg@kroah.com)
> Subject: [PATCH 3/3] hpsa: Convert DEVICE_ATTR macro usage to
> DEVICE_ATTR_RO|WR|WO
>
>
> Convert DEVICE_ATTR macro usage to DEVICE_ATTR_RO|WR|WO
> Changes forced some function names to change.
>
> Signed-off-by: Shane Seymour <shane.seymour@hp.com>
Signed-off-by: Don Brace <don.brace@pmcs.com>
^ permalink raw reply
* Re: [PATCH V3 4/5] mm: mmap: Add mmap flag to request VM_LOCKONFAULT
From: Paul Gortmaker @ 2015-07-18 19:11 UTC (permalink / raw)
To: Eric B Munson
Cc: Andrew Morton, Michal Hocko, Vlastimil Babka, LKML, linux-mm,
linux-arch, linux-api, cmetcalf, linux-next@vger.kernel.org
In-Reply-To: <1436288623-13007-5-git-send-email-emunson@akamai.com>
On Tue, Jul 7, 2015 at 1:03 PM, Eric B Munson <emunson@akamai.com> wrote:
> The cost of faulting in all memory to be locked can be very high when
> working with large mappings. If only portions of the mapping will be
> used this can incur a high penalty for locking.
>
> Now that we have the new VMA flag for the locked but not present state,
> expose it as an mmap option like MAP_LOCKED -> VM_LOCKED.
An automatic bisection on arch/tile leads to this commit:
5a5656f2c9b61c74c15f9ef3fa2e6513b6c237bb is the first bad commit
commit 5a5656f2c9b61c74c15f9ef3fa2e6513b6c237bb
Author: Eric B Munson <emunson@akamai.com>
Date: Thu Jul 16 10:09:22 2015 +1000
mm: mmap: add mmap flag to request VM_LOCKONFAULT
Fails with:
In file included from arch/tile/mm/init.c:24:
include/linux/mman.h: In function ‘calc_vm_flag_bits’:
include/linux/mman.h:90: error: ‘MAP_LOCKONFAULT’ undeclared (first
use in this function)
include/linux/mman.h:90: error: (Each undeclared identifier is
reported only once
include/linux/mman.h:90: error: for each function it appears in.)
In file included from arch/tile/mm/mmap.c:21:
include/linux/mman.h: In function ‘calc_vm_flag_bits’:
include/linux/mman.h:90: error: ‘MAP_LOCKONFAULT’ undeclared (first
use in this function)
include/linux/mman.h:90: error: (Each undeclared identifier is
reported only once
include/linux/mman.h:90: error: for each function it appears in.)
In file included from arch/tile/mm/fault.c:24:
include/linux/mman.h: In function ‘calc_vm_flag_bits’:
include/linux/mman.h:90: error: ‘MAP_LOCKONFAULT’ undeclared (first
use in this function)
include/linux/mman.h:90: error: (Each undeclared identifier is
reported only once
include/linux/mman.h:90: error: for each function it appears in.)
In file included from arch/tile/mm/hugetlbpage.c:27:
include/linux/mman.h: In function ‘calc_vm_flag_bits’:
include/linux/mman.h:90: error: ‘MAP_LOCKONFAULT’ undeclared (first
use in this function)
include/linux/mman.h:90: error: (Each undeclared identifier is
reported only once
include/linux/mman.h:90: error: for each function it appears in.)
make[1]: *** [arch/tile/mm/hugetlbpage.o] Error 1
http://kisskb.ellerman.id.au/kisskb/buildresult/12465365/
Paul.
--
^ permalink raw reply
* Re: [PATCH 08/24] proc: pick out a function to iterate task children
From: Oleg Nesterov @ 2015-07-18 21:22 UTC (permalink / raw)
To: Andrew Vagin
Cc: Andrey Vagin, linux-kernel-u79uwXL29TY76Z2rM5mHXA,
linux-api-u79uwXL29TY76Z2rM5mHXA, Andrew Morton, Cyrill Gorcunov,
Pavel Emelyanov, Roger Luethi, Arnd Bergmann,
Arnaldo Carvalho de Melo, David Ahern, Andy Lutomirski,
Pavel Odintsov
In-Reply-To: <20150717155728.GB6685-wo1vFcy6AUs@public.gmane.org>
On 07/17, Andrew Vagin wrote:
>
> On Tue, Jul 14, 2015 at 08:02:35PM +0200, Oleg Nesterov wrote:
> > On 07/06, Andrey Vagin wrote:
> > >
> > > -static struct pid *
> > > -get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
> > > +static struct task_struct *
> > > +task_next_child(struct task_struct *parent, struct task_struct *prev, unsigned int pos)
> > > {
> >
> > I won't really argue, just a question...
> >
> > So this patch changes it to accept/return task_struct rather pid. Why?
> > it is better to get/put "struct pid" only, not the whole task_struct.
> >
> > If another caller want task_struct, the necessary conversion is simple.
>
> Another caller wants task_struct.
>
> Currently this function receives pid and converts it into task_struct, then
> gets the next child and returns its pid.
Exactly because we try to avoid get_task_struct() if possible.
> So I try to avoid extra
> conversion in task_diag code.
Which is simple. And perhaps even iter->task can actually be iter->pid.
But as I said I won't really argue. And just in case, I personally think
this series makes sense, although I can't review the netlink interface.
Oleg.
^ permalink raw reply
* [PATCH] iio: Documentation: Remove bytes_per_datum attribute
From: Cristina Opriceana @ 2015-07-18 22:33 UTC (permalink / raw)
To: jic23-DgEjT+Ai2ygdnm+yROfE0A
Cc: daniel.baluta-ral2JQCrhuEAvxtiuMwx3w,
irina.tirdea-ral2JQCrhuEAvxtiuMwx3w, lars-Qo5EllUWu/uELgA04lAiVw,
octavian.purdila-ral2JQCrhuEAvxtiuMwx3w,
linux-api-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Remove sysfs bytes_per_datum device attribute ABI documentation
since the attribute is not present anymore.
Signed-off-by: Cristina Opriceana <cristina.opriceana-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
Documentation/ABI/testing/sysfs-bus-iio | 7 -------
1 file changed, 7 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 666a341..400d234 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1040,13 +1040,6 @@ Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Description:
Number of scans contained by the buffer.
-What: /sys/bus/iio/devices/iio:deviceX/buffer/bytes_per_datum
-KernelVersion: 2.6.37
-Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
-Description:
- Bytes per scan. Due to alignment fun, the scan may be larger
- than implied directly by the scan_element parameters.
-
What: /sys/bus/iio/devices/iio:deviceX/buffer/enable
KernelVersion: 2.6.35
Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
--
1.9.1
^ permalink raw reply related
* Re: [PATCH] iio: Documentation: Remove bytes_per_datum attribute
From: Jonathan Cameron @ 2015-07-19 9:29 UTC (permalink / raw)
To: Cristina Opriceana
Cc: daniel.baluta-ral2JQCrhuEAvxtiuMwx3w,
irina.tirdea-ral2JQCrhuEAvxtiuMwx3w, lars-Qo5EllUWu/uELgA04lAiVw,
octavian.purdila-ral2JQCrhuEAvxtiuMwx3w,
linux-api-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
In-Reply-To: <5fde6d1bda5e397469400876e3cc1c70243f31fb.1437257911.git.cristina.opriceana-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
On 18/07/15 23:33, Cristina Opriceana wrote:
> Remove sysfs bytes_per_datum device attribute ABI documentation
> since the attribute is not present anymore.
>
> Signed-off-by: Cristina Opriceana <cristina.opriceana-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Good spot.
Applied to the togreg branch of iio.git.
Jonathan
> ---
> Documentation/ABI/testing/sysfs-bus-iio | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 666a341..400d234 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -1040,13 +1040,6 @@ Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Description:
> Number of scans contained by the buffer.
>
> -What: /sys/bus/iio/devices/iio:deviceX/buffer/bytes_per_datum
> -KernelVersion: 2.6.37
> -Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> -Description:
> - Bytes per scan. Due to alignment fun, the scan may be larger
> - than implied directly by the scan_element parameters.
> -
> What: /sys/bus/iio/devices/iio:deviceX/buffer/enable
> KernelVersion: 2.6.35
> Contact: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>
^ permalink raw reply
* Re: [PATCH v4 3/5] pagemap: rework hugetlb and thp report
From: Kirill A. Shutemov @ 2015-07-19 11:10 UTC (permalink / raw)
To: Konstantin Khlebnikov
Cc: linux-mm, Andrew Morton, Naoya Horiguchi, Mark Williamson,
linux-kernel, linux-api
In-Reply-To: <20150714153738.29844.39039.stgit@buzz>
On Tue, Jul 14, 2015 at 06:37:39PM +0300, Konstantin Khlebnikov wrote:
> @@ -1073,35 +1047,48 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> pte_t *pte, *orig_pte;
> int err = 0;
>
> - if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
> - u64 flags = 0;
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + if (pmd_trans_huge_lock(pmdp, vma, &ptl) == 1) {
#ifdef is redundant. pmd_trans_huge_lock() always return 0 for !THP.
--
Kirill A. Shutemov
--
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^ permalink raw reply
* [PATCH -mm v9 0/8] idle memory tracking
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api-u79uwXL29TY76Z2rM5mHXA,
linux-doc-u79uwXL29TY76Z2rM5mHXA, linux-mm-Bw31MaZKKs3YtjvyW6yDsg,
cgroups-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Hi,
This patch set introduces a new user API for tracking user memory pages
that have not been used for a given period of time. The purpose of this
is to provide the userspace with the means of tracking a workload's
working set, i.e. the set of pages that are actively used by the
workload. Knowing the working set size can be useful for partitioning
the system more efficiently, e.g. by tuning memory cgroup limits
appropriately, or for job placement within a compute cluster.
It is based on top of v4.2-rc2-mmotm-2015-07-15-16-46
It applies without conflicts to v4.2-rc2-mmotm-2015-07-17-16-04 as well
---- USE CASES ----
The unified cgroup hierarchy has memory.low and memory.high knobs, which
are defined as the low and high boundaries for the workload working set
size. However, the working set size of a workload may be unknown or
change in time. With this patch set, one can periodically estimate the
amount of memory unused by each cgroup and tune their memory.low and
memory.high parameters accordingly, therefore optimizing the overall
memory utilization.
Another use case is balancing workloads within a compute cluster.
Knowing how much memory is not really used by a workload unit may help
take a more optimal decision when considering migrating the unit to
another node within the cluster.
Also, as noted by Minchan, this would be useful for per-process reclaim
(https://lwn.net/Articles/545668/). With idle tracking, we could reclaim idle
pages only by smart user memory manager.
---- USER API ----
The user API consists of two new proc files:
* /proc/kpageidle. This file implements a bitmap where each bit corresponds
to a page, indexed by PFN. When the bit is set, the corresponding page is
idle. A page is considered idle if it has not been accessed since it was
marked idle. To mark a page idle one should set the bit corresponding to the
page by writing to the file. A value written to the file is OR-ed with the
current bitmap value. Only user memory pages can be marked idle, for other
page types input is silently ignored. Writing to this file beyond max PFN
results in the ENXIO error. Only available when CONFIG_IDLE_PAGE_TRACKING is
set.
This file can be used to estimate the amount of pages that are not
used by a particular workload as follows:
1. mark all pages of interest idle by setting corresponding bits in the
/proc/kpageidle bitmap
2. wait until the workload accesses its working set
3. read /proc/kpageidle and count the number of bits set
* /proc/kpagecgroup. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
CONFIG_MEMCG is set.
This file can be used to find all pages (including unmapped file
pages) accounted to a particular cgroup. Using /proc/kpageidle, one
can then estimate the cgroup working set size.
For an example of using these files for estimating the amount of unused
memory pages per each memory cgroup, please see the script attached
below.
---- REASONING ----
The reason to introduce the new user API instead of using
/proc/PID/{clear_refs,smaps} is that the latter has two serious
drawbacks:
- it does not count unmapped file pages
- it affects the reclaimer logic
The new API attempts to overcome them both. For more details on how it
is achieved, please see the comment to patch 6.
---- CHANGE LOG ----
Changes in v9:
- add cond_resched to /proc/kpage* read/write loop (Andres)
- rebase on top of v4.2-rc2-mmotm-2015-07-15-16-46
Changes in v8:
- clear referenced/accessed bit in secondary ptes while accessing
/proc/kpageidle; this is required to estimate wss of KVM VMs (Andres)
- check the young flag when collapsing a huge page
- copy idle/young flags on page migration
Changes in v7:
This iteration addresses Andres's comments to v6:
- do not reuse page_referenced for clearing idle flag, introduce a
separate function instead; this way we won't issue expensive tlb
flushes on /proc/kpageidle read/write
- propagate young/idle flags from head to tail pages on thp split
- skip compound tail pages while reading/writing /proc/kpageidle
- cleanup page_referenced_one
Changes in v6:
- Split the patch introducing page_cgroup_ino helper to ease review.
- Rebase on top of v4.1-rc7-mmotm-2015-06-09-16-55
Changes in v5:
- Fix possible race between kpageidle_clear_pte_refs() and
__page_set_anon_rmap() by checking that a page is on an LRU list
under zone->lru_lock (Minchan).
- Export idle flag via /proc/kpageflags (Minchan).
- Rebase on top of 4.1-rc3.
Changes in v4:
This iteration primarily addresses Minchan's comments to v3:
- Implement /proc/kpageidle as a bitmap instead of using u64 per each page,
because there does not seem to be any future uses for the other 63 bits.
- Do not double-increase pra->referenced in page_referenced_one() if the page
was young and referenced recently.
- Remove the pointless (page_count == 0) check from kpageidle_get_page().
- Rename kpageidle_clear_refs() to kpageidle_clear_pte_refs().
- Improve comments to kpageidle-related functions.
- Rebase on top of 4.1-rc2.
Note it does not address Minchan's concern of possible __page_set_anon_rmap vs
page_referenced race (see https://lkml.org/lkml/2015/5/3/220) since it is still
unclear if this race can really happen (see https://lkml.org/lkml/2015/5/4/160)
Changes in v3:
- Enable CONFIG_IDLE_PAGE_TRACKING for 32 bit. Since this feature
requires two extra page flags and there is no space for them on 32
bit, page ext is used (thanks to Minchan Kim).
- Minor code cleanups and comments improved.
- Rebase on top of 4.1-rc1.
Changes in v2:
- The main difference from v1 is the API change. In v1 the user can
only set the idle flag for all pages at once, and for clearing the
Idle flag on pages accessed via page tables /proc/PID/clear_refs
should be used.
The main drawback of the v1 approach, as noted by Minchan, is that on
big machines setting the idle flag for each pages can result in CPU
bursts, which would be especially frustrating if the user only wanted
to estimate the amount of idle pages for a particular process or VMA.
With the new API a more fine-grained approach is possible: one can
read a process's /proc/PID/pagemap and set/check the Idle flag only
for those pages of the process's address space he or she is
interested in.
Another good point about the v2 API is that it is possible to limit
/proc/kpage* scanning rate when the user wants to estimate the total
number of idle pages, which is unachievable with the v1 approach.
- Make /proc/kpagecgroup return the ino of the closest online ancestor
in case the cgroup a page is charged to is offline.
- Fix /proc/PID/clear_refs not clearing Young page flag.
- Rebase on top of v4.0-rc6-mmotm-2015-04-01-14-54
v8: https://lkml.org/lkml/2015/7/15/587
v7: https://lkml.org/lkml/2015/7/11/119
v6: https://lkml.org/lkml/2015/6/12/301
v5: https://lkml.org/lkml/2015/5/12/449
v4: https://lkml.org/lkml/2015/5/7/580
v3: https://lkml.org/lkml/2015/4/28/224
v2: https://lkml.org/lkml/2015/4/7/260
v1: https://lkml.org/lkml/2015/3/18/794
---- PATCH SET STRUCTURE ----
The patch set is organized as follows:
- patch 1 adds page_cgroup_ino() helper for the sake of
/proc/kpagecgroup and patches 2-3 do related cleanup
- patch 4 adds /proc/kpagecgroup, which reports cgroup ino each page is
charged to
- patch 5 introduces a new mmu notifier callback, clear_young, which is
a lightweight version of clear_flush_young; it is used in patch 6
- patch 6 implements the idle page tracking feature, including the
userspace API, /proc/kpageidle
- patch 7 exports idle flag via /proc/kpageflags
---- SIMILAR WORKS ----
Originally, the patch for tracking idle memory was proposed back in 2011
by Michel Lespinasse (see http://lwn.net/Articles/459269/). The main
difference between Michel's patch and this one is that Michel
implemented a kernel space daemon for estimating idle memory size per
cgroup while this patch only provides the userspace with the minimal API
for doing the job, leaving the rest up to the userspace. However, they
both share the same idea of Idle/Young page flags to avoid affecting the
reclaimer logic.
---- PERFORMANCE EVALUATION ----
SPECjvm2008 (https://www.spec.org/jvm2008/) was used to evaluate the
performance impact introduced by this patch set. Three runs were carried
out:
- base: kernel without the patch
- patched: patched kernel, the feature is not used
- patched-active: patched kernel, 1 minute-period daemon is used for
tracking idle memory
For tracking idle memory, idlememstat utility was used:
https://github.com/locker/idlememstat
testcase base patched patched-active
compiler 537.40 ( 0.00)% 532.26 (-0.96)% 538.31 ( 0.17)%
compress 305.47 ( 0.00)% 301.08 (-1.44)% 300.71 (-1.56)%
crypto 284.32 ( 0.00)% 282.21 (-0.74)% 284.87 ( 0.19)%
derby 411.05 ( 0.00)% 413.44 ( 0.58)% 412.07 ( 0.25)%
mpegaudio 189.96 ( 0.00)% 190.87 ( 0.48)% 189.42 (-0.28)%
scimark.large 46.85 ( 0.00)% 46.41 (-0.94)% 47.83 ( 2.09)%
scimark.small 412.91 ( 0.00)% 415.41 ( 0.61)% 421.17 ( 2.00)%
serial 204.23 ( 0.00)% 213.46 ( 4.52)% 203.17 (-0.52)%
startup 36.76 ( 0.00)% 35.49 (-3.45)% 35.64 (-3.05)%
sunflow 115.34 ( 0.00)% 115.08 (-0.23)% 117.37 ( 1.76)%
xml 620.55 ( 0.00)% 619.95 (-0.10)% 620.39 (-0.03)%
composite 211.50 ( 0.00)% 211.15 (-0.17)% 211.67 ( 0.08)%
time idlememstat:
17.20user 65.16system 2:15:23elapsed 1%CPU (0avgtext+0avgdata 8476maxresident)k
448inputs+40outputs (1major+36052minor)pagefaults 0swaps
---- SCRIPT FOR COUNTING IDLE PAGES PER CGROUP ----
#! /usr/bin/python
#
import os
import stat
import errno
import struct
CGROUP_MOUNT = "/sys/fs/cgroup/memory"
BUFSIZE = 8 * 1024 # must be multiple of 8
def get_hugepage_size():
with open("/proc/meminfo", "r") as f:
for s in f:
k, v = s.split(":")
if k == "Hugepagesize":
return int(v.split()[0]) * 1024
PAGE_SIZE = os.sysconf("SC_PAGE_SIZE")
HUGEPAGE_SIZE = get_hugepage_size()
def set_idle():
f = open("/proc/kpageidle", "wb", BUFSIZE)
while True:
try:
f.write(struct.pack("Q", pow(2, 64) - 1))
except IOError as err:
if err.errno == errno.ENXIO:
break
raise
f.close()
def count_idle():
f_flags = open("/proc/kpageflags", "rb", BUFSIZE)
f_cgroup = open("/proc/kpagecgroup", "rb", BUFSIZE)
with open("/proc/kpageidle", "rb", BUFSIZE) as f:
while f.read(BUFSIZE): pass # update idle flag
idlememsz = {}
while True:
s1, s2 = f_flags.read(8), f_cgroup.read(8)
if not s1 or not s2:
break
flags, = struct.unpack('Q', s1)
cgino, = struct.unpack('Q', s2)
unevictable = (flags >> 18) & 1
huge = (flags >> 22) & 1
idle = (flags >> 25) & 1
if idle and not unevictable:
idlememsz[cgino] = idlememsz.get(cgino, 0) + \
(HUGEPAGE_SIZE if huge else PAGE_SIZE)
f_flags.close()
f_cgroup.close()
return idlememsz
if __name__ == "__main__":
print "Setting the idle flag for each page..."
set_idle()
raw_input("Wait until the workload accesses its working set, "
"then press Enter")
print "Counting idle pages..."
idlememsz = count_idle()
for dir, subdirs, files in os.walk(CGROUP_MOUNT):
ino = os.stat(dir)[stat.ST_INO]
print dir + ": " + str(idlememsz.get(ino, 0) / 1024) + " kB"
---- END SCRIPT ----
Comments are more than welcome.
Thanks,
Vladimir Davydov (8):
memcg: add page_cgroup_ino helper
hwpoison: use page_cgroup_ino for filtering by memcg
memcg: zap try_get_mem_cgroup_from_page
proc: add kpagecgroup file
mmu-notifier: add clear_young callback
proc: add kpageidle file
proc: export idle flag via kpageflags
proc: add cond_resched to /proc/kpage* read/write loop
Documentation/vm/pagemap.txt | 22 ++-
fs/proc/page.c | 282 +++++++++++++++++++++++++++++++++
fs/proc/task_mmu.c | 4 +-
include/linux/memcontrol.h | 10 +-
include/linux/mm.h | 98 ++++++++++++
include/linux/mmu_notifier.h | 44 +++++
include/linux/page-flags.h | 11 ++
include/linux/page_ext.h | 4 +
include/uapi/linux/kernel-page-flags.h | 1 +
mm/Kconfig | 12 ++
mm/debug.c | 4 +
mm/huge_memory.c | 11 +-
mm/hwpoison-inject.c | 5 +-
mm/memcontrol.c | 71 ++++-----
mm/memory-failure.c | 16 +-
mm/migrate.c | 5 +
mm/mmu_notifier.c | 17 ++
mm/page_ext.c | 3 +
mm/rmap.c | 5 +
mm/swap.c | 2 +
virt/kvm/kvm_main.c | 18 +++
21 files changed, 579 insertions(+), 66 deletions(-)
--
2.1.4
^ permalink raw reply
* [PATCH -mm v9 1/8] memcg: add page_cgroup_ino helper
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
This function returns the inode number of the closest online ancestor of
the memory cgroup a page is charged to. It is required for exporting
information about which page is charged to which cgroup to userspace,
which will be introduced by a following patch.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
---
include/linux/memcontrol.h | 1 +
mm/memcontrol.c | 23 +++++++++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d92b80b63c5c..99b0e43cac45 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -345,6 +345,7 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
}
struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page);
+unsigned long page_cgroup_ino(struct page *page);
static inline bool mem_cgroup_disabled(void)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1def8810880a..a91bc1ee964c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -441,6 +441,29 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
return &memcg->css;
}
+/**
+ * page_cgroup_ino - return inode number of the memcg a page is charged to
+ * @page: the page
+ *
+ * Look up the closest online ancestor of the memory cgroup @page is charged to
+ * and return its inode number or 0 if @page is not charged to any cgroup. It
+ * is safe to call this function without holding a reference to @page.
+ */
+unsigned long page_cgroup_ino(struct page *page)
+{
+ struct mem_cgroup *memcg;
+ unsigned long ino = 0;
+
+ rcu_read_lock();
+ memcg = READ_ONCE(page->mem_cgroup);
+ while (memcg && !(memcg->css.flags & CSS_ONLINE))
+ memcg = parent_mem_cgroup(memcg);
+ if (memcg)
+ ino = cgroup_ino(memcg->css.cgroup);
+ rcu_read_unlock();
+ return ino;
+}
+
static struct mem_cgroup_per_zone *
mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
{
--
2.1.4
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* [PATCH -mm v9 2/8] hwpoison: use page_cgroup_ino for filtering by memcg
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
Hwpoison allows to filter pages by memory cgroup ino. Currently, it
calls try_get_mem_cgroup_from_page to obtain the cgroup from a page and
then its ino using cgroup_ino, but now we have an apter method for that,
page_cgroup_ino, so use it instead.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
---
mm/hwpoison-inject.c | 5 +----
mm/memory-failure.c | 16 ++--------------
2 files changed, 3 insertions(+), 18 deletions(-)
diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index bf73ac17dad4..5015679014c1 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -45,12 +45,9 @@ static int hwpoison_inject(void *data, u64 val)
/*
* do a racy check with elevated page count, to make sure PG_hwpoison
* will only be set for the targeted owner (or on a free page).
- * We temporarily take page lock for try_get_mem_cgroup_from_page().
* memory_failure() will redo the check reliably inside page lock.
*/
- lock_page(hpage);
err = hwpoison_filter(hpage);
- unlock_page(hpage);
if (err)
goto put_out;
@@ -126,7 +123,7 @@ static int pfn_inject_init(void)
if (!dentry)
goto fail;
-#ifdef CONFIG_MEMCG_SWAP
+#ifdef CONFIG_MEMCG
dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
hwpoison_dir, &hwpoison_filter_memcg);
if (!dentry)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ef33ccf37224..97005396a507 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -130,27 +130,15 @@ static int hwpoison_filter_flags(struct page *p)
* can only guarantee that the page either belongs to the memcg tasks, or is
* a freed page.
*/
-#ifdef CONFIG_MEMCG_SWAP
+#ifdef CONFIG_MEMCG
u64 hwpoison_filter_memcg;
EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
static int hwpoison_filter_task(struct page *p)
{
- struct mem_cgroup *mem;
- struct cgroup_subsys_state *css;
- unsigned long ino;
-
if (!hwpoison_filter_memcg)
return 0;
- mem = try_get_mem_cgroup_from_page(p);
- if (!mem)
- return -EINVAL;
-
- css = &mem->css;
- ino = cgroup_ino(css->cgroup);
- css_put(css);
-
- if (ino != hwpoison_filter_memcg)
+ if (page_cgroup_ino(p) != hwpoison_filter_memcg)
return -EINVAL;
return 0;
--
2.1.4
--
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* [PATCH -mm v9 3/8] memcg: zap try_get_mem_cgroup_from_page
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
It is only used in mem_cgroup_try_charge, so fold it in and zap it.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
include/linux/memcontrol.h | 9 +--------
mm/memcontrol.c | 48 ++++++++++++----------------------------------
2 files changed, 13 insertions(+), 44 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 99b0e43cac45..d644aadfdd0d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -305,11 +305,9 @@ struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
-
-struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
-
struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
+
static inline
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
return css ? container_of(css, struct mem_cgroup, css) : NULL;
@@ -556,11 +554,6 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
return &zone->lruvec;
}
-static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
-{
- return NULL;
-}
-
static inline bool mm_match_cgroup(struct mm_struct *mm,
struct mem_cgroup *memcg)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a91bc1ee964c..b9c76a0906f9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2094,40 +2094,6 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
css_put_many(&memcg->css, nr_pages);
}
-/*
- * try_get_mem_cgroup_from_page - look up page's memcg association
- * @page: the page
- *
- * Look up, get a css reference, and return the memcg that owns @page.
- *
- * The page must be locked to prevent racing with swap-in and page
- * cache charges. If coming from an unlocked page table, the caller
- * must ensure the page is on the LRU or this can race with charging.
- */
-struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
-{
- struct mem_cgroup *memcg;
- unsigned short id;
- swp_entry_t ent;
-
- VM_BUG_ON_PAGE(!PageLocked(page), page);
-
- memcg = page->mem_cgroup;
- if (memcg) {
- if (!css_tryget_online(&memcg->css))
- memcg = NULL;
- } else if (PageSwapCache(page)) {
- ent.val = page_private(page);
- id = lookup_swap_cgroup_id(ent);
- rcu_read_lock();
- memcg = mem_cgroup_from_id(id);
- if (memcg && !css_tryget_online(&memcg->css))
- memcg = NULL;
- rcu_read_unlock();
- }
- return memcg;
-}
-
static void lock_page_lru(struct page *page, int *isolated)
{
struct zone *zone = page_zone(page);
@@ -5327,8 +5293,20 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
* the page lock, which serializes swap cache removal, which
* in turn serializes uncharging.
*/
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
if (page->mem_cgroup)
goto out;
+
+ if (do_swap_account) {
+ swp_entry_t ent = { .val = page_private(page), };
+ unsigned short id = lookup_swap_cgroup_id(ent);
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_id(id);
+ if (memcg && !css_tryget_online(&memcg->css))
+ memcg = NULL;
+ rcu_read_unlock();
+ }
}
if (PageTransHuge(page)) {
@@ -5336,8 +5314,6 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
}
- if (do_swap_account && PageSwapCache(page))
- memcg = try_get_mem_cgroup_from_page(page);
if (!memcg)
memcg = get_mem_cgroup_from_mm(mm);
--
2.1.4
--
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* [PATCH -mm v9 4/8] proc: add kpagecgroup file
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
/proc/kpagecgroup contains a 64-bit inode number of the memory cgroup
each page is charged to, indexed by PFN. Having this information is
useful for estimating a cgroup working set size.
The file is present if CONFIG_PROC_PAGE_MONITOR && CONFIG_MEMCG.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
Documentation/vm/pagemap.txt | 6 ++++-
fs/proc/page.c | 53 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index 56faec0f73f7..3a37ed184258 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -5,7 +5,7 @@ pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow
userspace programs to examine the page tables and related information by
reading files in /proc.
-There are three components to pagemap:
+There are four components to pagemap:
* /proc/pid/pagemap. This file lets a userspace process find out which
physical frame each virtual page is mapped to. It contains one 64-bit
@@ -66,6 +66,10 @@ There are three components to pagemap:
23. BALLOON
24. ZERO_PAGE
+ * /proc/kpagecgroup. This file contains a 64-bit inode number of the
+ memory cgroup each page is charged to, indexed by PFN. Only available when
+ CONFIG_MEMCG is set.
+
Short descriptions to the page flags:
0. LOCKED
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 7eee2d8b97d9..70d23245dd43 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -9,6 +9,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/hugetlb.h>
+#include <linux/memcontrol.h>
#include <linux/kernel-page-flags.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -225,10 +226,62 @@ static const struct file_operations proc_kpageflags_operations = {
.read = kpageflags_read,
};
+#ifdef CONFIG_MEMCG
+static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ u64 __user *out = (u64 __user *)buf;
+ struct page *ppage;
+ unsigned long src = *ppos;
+ unsigned long pfn;
+ ssize_t ret = 0;
+ u64 ino;
+
+ pfn = src / KPMSIZE;
+ count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
+ if (src & KPMMASK || count & KPMMASK)
+ return -EINVAL;
+
+ while (count > 0) {
+ if (pfn_valid(pfn))
+ ppage = pfn_to_page(pfn);
+ else
+ ppage = NULL;
+
+ if (ppage)
+ ino = page_cgroup_ino(ppage);
+ else
+ ino = 0;
+
+ if (put_user(ino, out)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ pfn++;
+ out++;
+ count -= KPMSIZE;
+ }
+
+ *ppos += (char __user *)out - buf;
+ if (!ret)
+ ret = (char __user *)out - buf;
+ return ret;
+}
+
+static const struct file_operations proc_kpagecgroup_operations = {
+ .llseek = mem_lseek,
+ .read = kpagecgroup_read,
+};
+#endif /* CONFIG_MEMCG */
+
static int __init proc_page_init(void)
{
proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
+#ifdef CONFIG_MEMCG
+ proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);
+#endif
return 0;
}
fs_initcall(proc_page_init);
--
2.1.4
--
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* [PATCH -mm v9 5/8] mmu-notifier: add clear_young callback
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
In the scope of the idle memory tracking feature, which is introduced by
the following patch, we need to clear the referenced/accessed bit not
only in primary, but also in secondary ptes. The latter is required in
order to estimate wss of KVM VMs. At the same time we want to avoid
flushing tlb, because it is quite expensive and it won't really affect
the final result.
Currently, there is no function for clearing pte young bit that would
meet our requirements, so this patch introduces one. To achieve that we
have to add a new mmu-notifier callback, clear_young, since there is no
method for testing-and-clearing a secondary pte w/o flushing tlb. The
new method is not mandatory and currently only implemented by KVM.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
---
include/linux/mmu_notifier.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
mm/mmu_notifier.c | 17 +++++++++++++++++
virt/kvm/kvm_main.c | 18 ++++++++++++++++++
3 files changed, 79 insertions(+)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 61cd67f4d788..a5b17137c683 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -66,6 +66,16 @@ struct mmu_notifier_ops {
unsigned long end);
/*
+ * clear_young is a lightweight version of clear_flush_young. Like the
+ * latter, it is supposed to test-and-clear the young/accessed bitflag
+ * in the secondary pte, but it may omit flushing the secondary tlb.
+ */
+ int (*clear_young)(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end);
+
+ /*
* test_young is called to check the young/accessed bitflag in
* the secondary pte. This is used to know if the page is
* frequently used without actually clearing the flag or tearing
@@ -203,6 +213,9 @@ extern void __mmu_notifier_release(struct mm_struct *mm);
extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
unsigned long start,
unsigned long end);
+extern int __mmu_notifier_clear_young(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end);
extern int __mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address);
extern void __mmu_notifier_change_pte(struct mm_struct *mm,
@@ -231,6 +244,15 @@ static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
return 0;
}
+static inline int mmu_notifier_clear_young(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ if (mm_has_notifiers(mm))
+ return __mmu_notifier_clear_young(mm, start, end);
+ return 0;
+}
+
static inline int mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address)
{
@@ -311,6 +333,28 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
__young; \
})
+#define ptep_clear_young_notify(__vma, __address, __ptep) \
+({ \
+ int __young; \
+ struct vm_area_struct *___vma = __vma; \
+ unsigned long ___address = __address; \
+ __young = ptep_test_and_clear_young(___vma, ___address, __ptep);\
+ __young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
+ ___address + PAGE_SIZE); \
+ __young; \
+})
+
+#define pmdp_clear_young_notify(__vma, __address, __pmdp) \
+({ \
+ int __young; \
+ struct vm_area_struct *___vma = __vma; \
+ unsigned long ___address = __address; \
+ __young = pmdp_test_and_clear_young(___vma, ___address, __pmdp);\
+ __young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
+ ___address + PMD_SIZE); \
+ __young; \
+})
+
#define ptep_clear_flush_notify(__vma, __address, __ptep) \
({ \
unsigned long ___addr = __address & PAGE_MASK; \
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 3b9b3d0741b2..5fbdd367bbed 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -123,6 +123,23 @@ int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
return young;
}
+int __mmu_notifier_clear_young(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct mmu_notifier *mn;
+ int young = 0, id;
+
+ id = srcu_read_lock(&srcu);
+ hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
+ if (mn->ops->clear_young)
+ young |= mn->ops->clear_young(mn, mm, start, end);
+ }
+ srcu_read_unlock(&srcu, id);
+
+ return young;
+}
+
int __mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address)
{
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8b8a44453670..ff4173ce6924 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -387,6 +387,23 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
return young;
}
+static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct kvm *kvm = mmu_notifier_to_kvm(mn);
+ int young, idx;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ spin_lock(&kvm->mmu_lock);
+ young = kvm_age_hva(kvm, start, end);
+ spin_unlock(&kvm->mmu_lock);
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ return young;
+}
+
static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long address)
@@ -419,6 +436,7 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
.invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
.invalidate_range_end = kvm_mmu_notifier_invalidate_range_end,
.clear_flush_young = kvm_mmu_notifier_clear_flush_young,
+ .clear_young = kvm_mmu_notifier_clear_young,
.test_young = kvm_mmu_notifier_test_young,
.change_pte = kvm_mmu_notifier_change_pte,
.release = kvm_mmu_notifier_release,
--
2.1.4
--
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* [PATCH -mm v9 6/8] proc: add kpageidle file
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
Knowing the portion of memory that is not used by a certain application
or memory cgroup (idle memory) can be useful for partitioning the system
efficiently, e.g. by setting memory cgroup limits appropriately.
Currently, the only means to estimate the amount of idle memory provided
by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
access bit for all pages mapped to a particular process by writing 1 to
clear_refs, wait for some time, and then count smaps:Referenced.
However, this method has two serious shortcomings:
- it does not count unmapped file pages
- it affects the reclaimer logic
To overcome these drawbacks, this patch introduces two new page flags,
Idle and Young, and a new proc file, /proc/kpageidle. A page's Idle flag
can only be set from userspace by setting bit in /proc/kpageidle at the
offset corresponding to the page, and it is cleared whenever the page is
accessed either through page tables (it is cleared in page_referenced()
in this case) or using the read(2) system call (mark_page_accessed()).
Thus by setting the Idle flag for pages of a particular workload, which
can be found e.g. by reading /proc/PID/pagemap, waiting for some time to
let the workload access its working set, and then reading the kpageidle
file, one can estimate the amount of pages that are not used by the
workload.
The Young page flag is used to avoid interference with the memory
reclaimer. A page's Young flag is set whenever the Access bit of a page
table entry pointing to the page is cleared by writing to kpageidle. If
page_referenced() is called on a Young page, it will add 1 to its return
value, therefore concealing the fact that the Access bit was cleared.
Note, since there is no room for extra page flags on 32 bit, this
feature uses extended page flags when compiled on 32 bit.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
Documentation/vm/pagemap.txt | 12 ++-
fs/proc/page.c | 218 +++++++++++++++++++++++++++++++++++++++++++
fs/proc/task_mmu.c | 4 +-
include/linux/mm.h | 98 +++++++++++++++++++
include/linux/page-flags.h | 11 +++
include/linux/page_ext.h | 4 +
mm/Kconfig | 12 +++
mm/debug.c | 4 +
mm/huge_memory.c | 11 ++-
mm/migrate.c | 5 +
mm/page_ext.c | 3 +
mm/rmap.c | 5 +
mm/swap.c | 2 +
13 files changed, 385 insertions(+), 4 deletions(-)
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index 3a37ed184258..34fe828c3007 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -5,7 +5,7 @@ pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow
userspace programs to examine the page tables and related information by
reading files in /proc.
-There are four components to pagemap:
+There are five components to pagemap:
* /proc/pid/pagemap. This file lets a userspace process find out which
physical frame each virtual page is mapped to. It contains one 64-bit
@@ -70,6 +70,16 @@ There are four components to pagemap:
memory cgroup each page is charged to, indexed by PFN. Only available when
CONFIG_MEMCG is set.
+ * /proc/kpageidle. This file implements a bitmap where each bit corresponds
+ to a page, indexed by PFN. When the bit is set, the corresponding page is
+ idle. A page is considered idle if it has not been accessed since it was
+ marked idle. To mark a page idle one should set the bit corresponding to the
+ page by writing to the file. A value written to the file is OR-ed with the
+ current bitmap value. Only user memory pages can be marked idle, for other
+ page types input is silently ignored. Writing to this file beyond max PFN
+ results in the ENXIO error. Only available when CONFIG_IDLE_PAGE_TRACKING is
+ set.
+
Short descriptions to the page flags:
0. LOCKED
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 70d23245dd43..273537885ab4 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -5,6 +5,8 @@
#include <linux/ksm.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
+#include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
#include <linux/huge_mm.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
@@ -16,6 +18,7 @@
#define KPMSIZE sizeof(u64)
#define KPMMASK (KPMSIZE - 1)
+#define KPMBITS (KPMSIZE * BITS_PER_BYTE)
/* /proc/kpagecount - an array exposing page counts
*
@@ -275,6 +278,217 @@ static const struct file_operations proc_kpagecgroup_operations = {
};
#endif /* CONFIG_MEMCG */
+#ifdef CONFIG_IDLE_PAGE_TRACKING
+/*
+ * Idle page tracking only considers user memory pages, for other types of
+ * pages the idle flag is always unset and an attempt to set it is silently
+ * ignored.
+ *
+ * We treat a page as a user memory page if it is on an LRU list, because it is
+ * always safe to pass such a page to rmap_walk(), which is essential for idle
+ * page tracking. With such an indicator of user pages we can skip isolated
+ * pages, but since there are not usually many of them, it will hardly affect
+ * the overall result.
+ *
+ * This function tries to get a user memory page by pfn as described above.
+ */
+static struct page *kpageidle_get_page(unsigned long pfn)
+{
+ struct page *page;
+ struct zone *zone;
+
+ if (!pfn_valid(pfn))
+ return NULL;
+
+ page = pfn_to_page(pfn);
+ if (!page || !PageLRU(page) ||
+ !get_page_unless_zero(page))
+ return NULL;
+
+ zone = page_zone(page);
+ spin_lock_irq(&zone->lru_lock);
+ if (unlikely(!PageLRU(page))) {
+ put_page(page);
+ page = NULL;
+ }
+ spin_unlock_irq(&zone->lru_lock);
+ return page;
+}
+
+static int kpageidle_clear_pte_refs_one(struct page *page,
+ struct vm_area_struct *vma,
+ unsigned long addr, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ pmd_t *pmd;
+ pte_t *pte;
+ bool referenced = false;
+
+ if (unlikely(PageTransHuge(page))) {
+ pmd = page_check_address_pmd(page, mm, addr,
+ PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
+ if (pmd) {
+ referenced = pmdp_clear_young_notify(vma, addr, pmd);
+ spin_unlock(ptl);
+ }
+ } else {
+ pte = page_check_address(page, mm, addr, &ptl, 0);
+ if (pte) {
+ referenced = ptep_clear_young_notify(vma, addr, pte);
+ pte_unmap_unlock(pte, ptl);
+ }
+ }
+ if (referenced) {
+ clear_page_idle(page);
+ /*
+ * We cleared the referenced bit in a mapping to this page. To
+ * avoid interference with page reclaim, mark it young so that
+ * page_referenced() will return > 0.
+ */
+ set_page_young(page);
+ }
+ return SWAP_AGAIN;
+}
+
+static void kpageidle_clear_pte_refs(struct page *page)
+{
+ struct rmap_walk_control rwc = {
+ .rmap_one = kpageidle_clear_pte_refs_one,
+ .anon_lock = page_lock_anon_vma_read,
+ };
+ bool need_lock;
+
+ if (!page_mapped(page) ||
+ !page_rmapping(page))
+ return;
+
+ need_lock = !PageAnon(page) || PageKsm(page);
+ if (need_lock && !trylock_page(page))
+ return;
+
+ rmap_walk(page, &rwc);
+
+ if (need_lock)
+ unlock_page(page);
+}
+
+static ssize_t kpageidle_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ u64 __user *out = (u64 __user *)buf;
+ struct page *page;
+ unsigned long pfn, end_pfn;
+ ssize_t ret = 0;
+ u64 idle_bitmap = 0;
+ int bit;
+
+ if (*ppos & KPMMASK || count & KPMMASK)
+ return -EINVAL;
+
+ pfn = *ppos * BITS_PER_BYTE;
+ if (pfn >= max_pfn)
+ return 0;
+
+ end_pfn = pfn + count * BITS_PER_BYTE;
+ if (end_pfn > max_pfn)
+ end_pfn = ALIGN(max_pfn, KPMBITS);
+
+ for (; pfn < end_pfn; pfn++) {
+ bit = pfn % KPMBITS;
+ page = kpageidle_get_page(pfn);
+ if (page) {
+ if (page_is_idle(page)) {
+ /*
+ * The page might have been referenced via a
+ * pte, in which case it is not idle. Clear
+ * refs and recheck.
+ */
+ kpageidle_clear_pte_refs(page);
+ if (page_is_idle(page))
+ idle_bitmap |= 1ULL << bit;
+ }
+ put_page(page);
+ }
+ if (bit == KPMBITS - 1) {
+ if (put_user(idle_bitmap, out)) {
+ ret = -EFAULT;
+ break;
+ }
+ idle_bitmap = 0;
+ out++;
+ }
+ }
+
+ *ppos += (char __user *)out - buf;
+ if (!ret)
+ ret = (char __user *)out - buf;
+ return ret;
+}
+
+static ssize_t kpageidle_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ const u64 __user *in = (const u64 __user *)buf;
+ struct page *page;
+ unsigned long pfn, end_pfn;
+ ssize_t ret = 0;
+ u64 idle_bitmap = 0;
+ int bit;
+
+ if (*ppos & KPMMASK || count & KPMMASK)
+ return -EINVAL;
+
+ pfn = *ppos * BITS_PER_BYTE;
+ if (pfn >= max_pfn)
+ return -ENXIO;
+
+ end_pfn = pfn + count * BITS_PER_BYTE;
+ if (end_pfn > max_pfn)
+ end_pfn = ALIGN(max_pfn, KPMBITS);
+
+ for (; pfn < end_pfn; pfn++) {
+ bit = pfn % KPMBITS;
+ if (bit == 0) {
+ if (get_user(idle_bitmap, in)) {
+ ret = -EFAULT;
+ break;
+ }
+ in++;
+ }
+ if (idle_bitmap >> bit & 1) {
+ page = kpageidle_get_page(pfn);
+ if (page) {
+ kpageidle_clear_pte_refs(page);
+ set_page_idle(page);
+ put_page(page);
+ }
+ }
+ }
+
+ *ppos += (const char __user *)in - buf;
+ if (!ret)
+ ret = (const char __user *)in - buf;
+ return ret;
+}
+
+static const struct file_operations proc_kpageidle_operations = {
+ .llseek = mem_lseek,
+ .read = kpageidle_read,
+ .write = kpageidle_write,
+};
+
+#ifndef CONFIG_64BIT
+static bool need_page_idle(void)
+{
+ return true;
+}
+struct page_ext_operations page_idle_ops = {
+ .need = need_page_idle,
+};
+#endif
+#endif /* CONFIG_IDLE_PAGE_TRACKING */
+
static int __init proc_page_init(void)
{
proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
@@ -282,6 +496,10 @@ static int __init proc_page_init(void)
#ifdef CONFIG_MEMCG
proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);
#endif
+#ifdef CONFIG_IDLE_PAGE_TRACKING
+ proc_create("kpageidle", S_IRUSR | S_IWUSR, NULL,
+ &proc_kpageidle_operations);
+#endif
return 0;
}
fs_initcall(proc_page_init);
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 860bb0f30f14..7c9a17414106 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -459,7 +459,7 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
mss->resident += size;
/* Accumulate the size in pages that have been accessed. */
- if (young || PageReferenced(page))
+ if (young || page_is_young(page) || PageReferenced(page))
mss->referenced += size;
mapcount = page_mapcount(page);
if (mapcount >= 2) {
@@ -808,6 +808,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
/* Clear accessed and referenced bits. */
pmdp_test_and_clear_young(vma, addr, pmd);
+ test_and_clear_page_young(page);
ClearPageReferenced(page);
out:
spin_unlock(ptl);
@@ -835,6 +836,7 @@ out:
/* Clear accessed and referenced bits. */
ptep_test_and_clear_young(vma, addr, pte);
+ test_and_clear_page_young(page);
ClearPageReferenced(page);
}
pte_unmap_unlock(pte - 1, ptl);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c3a2b37365f6..0e62be7d5138 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2202,5 +2202,103 @@ void __init setup_nr_node_ids(void);
static inline void setup_nr_node_ids(void) {}
#endif
+#ifdef CONFIG_IDLE_PAGE_TRACKING
+#ifdef CONFIG_64BIT
+static inline bool page_is_young(struct page *page)
+{
+ return PageYoung(page);
+}
+
+static inline void set_page_young(struct page *page)
+{
+ SetPageYoung(page);
+}
+
+static inline bool test_and_clear_page_young(struct page *page)
+{
+ return TestClearPageYoung(page);
+}
+
+static inline bool page_is_idle(struct page *page)
+{
+ return PageIdle(page);
+}
+
+static inline void set_page_idle(struct page *page)
+{
+ SetPageIdle(page);
+}
+
+static inline void clear_page_idle(struct page *page)
+{
+ ClearPageIdle(page);
+}
+#else /* !CONFIG_64BIT */
+/*
+ * If there is not enough space to store Idle and Young bits in page flags, use
+ * page ext flags instead.
+ */
+extern struct page_ext_operations page_idle_ops;
+
+static inline bool page_is_young(struct page *page)
+{
+ return test_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
+}
+
+static inline void set_page_young(struct page *page)
+{
+ set_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
+}
+
+static inline bool test_and_clear_page_young(struct page *page)
+{
+ return test_and_clear_bit(PAGE_EXT_YOUNG,
+ &lookup_page_ext(page)->flags);
+}
+
+static inline bool page_is_idle(struct page *page)
+{
+ return test_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+}
+
+static inline void set_page_idle(struct page *page)
+{
+ set_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+}
+
+static inline void clear_page_idle(struct page *page)
+{
+ clear_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+}
+#endif /* CONFIG_64BIT */
+#else /* !CONFIG_IDLE_PAGE_TRACKING */
+static inline bool page_is_young(struct page *page)
+{
+ return false;
+}
+
+static inline void set_page_young(struct page *page)
+{
+}
+
+static inline bool test_and_clear_page_young(struct page *page)
+{
+ return false;
+}
+
+static inline bool page_is_idle(struct page *page)
+{
+ return false;
+}
+
+static inline void set_page_idle(struct page *page)
+{
+}
+
+static inline void clear_page_idle(struct page *page)
+{
+}
+#endif /* CONFIG_IDLE_PAGE_TRACKING */
+
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 91b7f9b2b774..478f2241f284 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -109,6 +109,10 @@ enum pageflags {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
PG_compound_lock,
#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+ PG_young,
+ PG_idle,
+#endif
__NR_PAGEFLAGS,
/* Filesystems */
@@ -363,6 +367,13 @@ PAGEFLAG_FALSE(HWPoison)
#define __PG_HWPOISON 0
#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+TESTPAGEFLAG(Young, young, PF_ANY)
+SETPAGEFLAG(Young, young, PF_ANY)
+TESTCLEARFLAG(Young, young, PF_ANY)
+PAGEFLAG(Idle, idle, PF_ANY)
+#endif
+
/*
* On an anonymous page mapped into a user virtual memory area,
* page->mapping points to its anon_vma, not to a struct address_space;
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index c42981cd99aa..17f118a82854 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -26,6 +26,10 @@ enum page_ext_flags {
PAGE_EXT_DEBUG_POISON, /* Page is poisoned */
PAGE_EXT_DEBUG_GUARD,
PAGE_EXT_OWNER,
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+ PAGE_EXT_YOUNG,
+ PAGE_EXT_IDLE,
+#endif
};
/*
diff --git a/mm/Kconfig b/mm/Kconfig
index e79de2bd12cd..db817e2c2ec8 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -654,3 +654,15 @@ config DEFERRED_STRUCT_PAGE_INIT
when kswapd starts. This has a potential performance impact on
processes running early in the lifetime of the systemm until kswapd
finishes the initialisation.
+
+config IDLE_PAGE_TRACKING
+ bool "Enable idle page tracking"
+ select PROC_PAGE_MONITOR
+ select PAGE_EXTENSION if !64BIT
+ help
+ This feature allows to estimate the amount of user pages that have
+ not been touched during a given period of time. This information can
+ be useful to tune memory cgroup limits and/or for job placement
+ within a compute cluster.
+
+ See Documentation/vm/pagemap.txt for more details.
diff --git a/mm/debug.c b/mm/debug.c
index 76089ddf99ea..6c1b3ea61bfd 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -48,6 +48,10 @@ static const struct trace_print_flags pageflag_names[] = {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
{1UL << PG_compound_lock, "compound_lock" },
#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+ {1UL << PG_young, "young" },
+ {1UL << PG_idle, "idle" },
+#endif
};
static void dump_flags(unsigned long flags,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8f9a334a6c66..5ab46adca104 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1806,6 +1806,11 @@ static void __split_huge_page_refcount(struct page *page,
/* clear PageTail before overwriting first_page */
smp_wmb();
+ if (page_is_young(page))
+ set_page_young(page_tail);
+ if (page_is_idle(page))
+ set_page_idle(page_tail);
+
/*
* __split_huge_page_splitting() already set the
* splitting bit in all pmd that could map this
@@ -2311,7 +2316,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
VM_BUG_ON_PAGE(PageLRU(page), page);
/* If there is no mapped pte young don't collapse the page */
- if (pte_young(pteval) || PageReferenced(page) ||
+ if (pte_young(pteval) ||
+ page_is_young(page) || PageReferenced(page) ||
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
@@ -2738,7 +2744,8 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
*/
if (page_count(page) != 1 + !!PageSwapCache(page))
goto out_unmap;
- if (pte_young(pteval) || PageReferenced(page) ||
+ if (pte_young(pteval) ||
+ page_is_young(page) || PageReferenced(page) ||
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
diff --git a/mm/migrate.c b/mm/migrate.c
index d3529d620a5b..d86cec005aa6 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -524,6 +524,11 @@ void migrate_page_copy(struct page *newpage, struct page *page)
__set_page_dirty_nobuffers(newpage);
}
+ if (page_is_young(page))
+ set_page_young(newpage);
+ if (page_is_idle(page))
+ set_page_idle(newpage);
+
/*
* Copy NUMA information to the new page, to prevent over-eager
* future migrations of this same page.
diff --git a/mm/page_ext.c b/mm/page_ext.c
index d86fd2f5353f..e4b3af054bf2 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -59,6 +59,9 @@ static struct page_ext_operations *page_ext_ops[] = {
#ifdef CONFIG_PAGE_OWNER
&page_owner_ops,
#endif
+#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+ &page_idle_ops,
+#endif
};
static unsigned long total_usage;
diff --git a/mm/rmap.c b/mm/rmap.c
index 30812e9042ae..9e411aa03176 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -900,6 +900,11 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
pte_unmap_unlock(pte, ptl);
}
+ if (referenced)
+ clear_page_idle(page);
+ if (test_and_clear_page_young(page))
+ referenced++;
+
if (referenced) {
pra->referenced++;
pra->vm_flags |= vma->vm_flags;
diff --git a/mm/swap.c b/mm/swap.c
index d398860badd1..04b6ce51bcf0 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -623,6 +623,8 @@ void mark_page_accessed(struct page *page)
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
}
+ if (page_is_idle(page))
+ clear_page_idle(page);
}
EXPORT_SYMBOL(mark_page_accessed);
--
2.1.4
--
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^ permalink raw reply related
* [PATCH -mm v9 7/8] proc: export idle flag via kpageflags
From: Vladimir Davydov @ 2015-07-19 12:31 UTC (permalink / raw)
To: Andrew Morton
Cc: Andres Lagar-Cavilla, Minchan Kim, Raghavendra K T,
Johannes Weiner, Michal Hocko, Greg Thelen, Michel Lespinasse,
David Rientjes, Pavel Emelyanov, Cyrill Gorcunov, Jonathan Corbet,
linux-api, linux-doc, linux-mm, cgroups, linux-kernel
In-Reply-To: <cover.1437303956.git.vdavydov@parallels.com>
As noted by Minchan, a benefit of reading idle flag from
/proc/kpageflags is that one can easily filter dirty and/or unevictable
pages while estimating the size of unused memory.
Note that idle flag read from /proc/kpageflags may be stale in case the
page was accessed via a PTE, because it would be too costly to iterate
over all page mappings on each /proc/kpageflags read to provide an
up-to-date value. To make sure the flag is up-to-date one has to read
/proc/kpageidle first.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
---
Documentation/vm/pagemap.txt | 6 ++++++
fs/proc/page.c | 3 +++
include/uapi/linux/kernel-page-flags.h | 1 +
3 files changed, 10 insertions(+)
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index 34fe828c3007..538735465693 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -65,6 +65,7 @@ There are five components to pagemap:
22. THP
23. BALLOON
24. ZERO_PAGE
+ 25. IDLE
* /proc/kpagecgroup. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
@@ -125,6 +126,11 @@ Short descriptions to the page flags:
24. ZERO_PAGE
zero page for pfn_zero or huge_zero page
+25. IDLE
+ page has not been accessed since it was marked idle (see /proc/kpageidle)
+ Note that this flag may be stale in case the page was accessed via a PTE.
+ To make sure the flag is up-to-date one has to read /proc/kpageidle first.
+
[IO related page flags]
1. ERROR IO error occurred
3. UPTODATE page has up-to-date data
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 273537885ab4..13dcb823fe4e 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -150,6 +150,9 @@ u64 stable_page_flags(struct page *page)
if (PageBalloon(page))
u |= 1 << KPF_BALLOON;
+ if (page_is_idle(page))
+ u |= 1 << KPF_IDLE;
+
u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index a6c4962e5d46..5da5f8751ce7 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -33,6 +33,7 @@
#define KPF_THP 22
#define KPF_BALLOON 23
#define KPF_ZERO_PAGE 24
+#define KPF_IDLE 25
#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
--
2.1.4
--
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