linux-kernel - Re: [PATCHv2 3/7] mm/memblock: introduce allocation boundary for tracing purpose

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 14 Jan 2019 17:13:48 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Yinghai Lu <yinghai@...nel.org>,
        Tejun Heo <tj@...nel.org>, Chao Fan <fanc.fnst@...fujitsu.com>,
        Baoquan He <bhe@...hat.com>, Juergen Gross <jgross@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>, x86@...nel.org,
        linux-acpi@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv2 3/7] mm/memblock: introduce allocation boundary for
 tracing purpose

On Mon, Jan 14, 2019 at 4:50 PM Mike Rapoport <rppt@...ux.ibm.com> wrote:
>
> On Mon, Jan 14, 2019 at 04:33:50PM +0800, Pingfan Liu wrote:
> > On Mon, Jan 14, 2019 at 3:51 PM Mike Rapoport <rppt@...ux.ibm.com> wrote:
> > >
> > > Hi Pingfan,
> > >
> > > On Fri, Jan 11, 2019 at 01:12:53PM +0800, Pingfan Liu wrote:
> > > > During boot time, there is requirement to tell whether a series of func
> > > > call will consume memory or not. For some reason, a temporary memory
> > > > resource can be loan to those func through memblock allocator, but at a
> > > > check point, all of the loan memory should be turned back.
> > > > A typical using style:
> > > >  -1. find a usable range by memblock_find_in_range(), said, [A,B]
> > > >  -2. before calling a series of func, memblock_set_current_limit(A,B,true)
> > > >  -3. call funcs
> > > >  -4. memblock_find_in_range(A,B,B-A,1), if failed, then some memory is not
> > > >      turned back.
> > > >  -5. reset the original limit
> > > >
> > > > E.g. in the case of hotmovable memory, some acpi routines should be called,
> > > > and they are not allowed to own some movable memory. Although at present
> > > > these functions do not consume memory, but later, if changed without
> > > > awareness, they may do. With the above method, the allocation can be
> > > > detected, and pr_warn() to ask people to resolve it.
> > >
> > > To ensure there were that a sequence of function calls didn't create new
> > > memblock allocations you can simply check the number of the reserved
> > > regions before and after that sequence.
> > >
> > Yes, thank you point out it.
> >
> > > Still, I'm not sure it would be practical to try tracking what code that's called
> > > from x86::setup_arch() did memory allocation.
> > > Probably a better approach is to verify no memory ended up in the movable
> > > areas after their extents are known.
> > >
> > It is a probability problem whether allocated memory sit on hotmovable
> > memory or not. And if warning based on the verification, then it is
> > also a probability problem and maybe we will miss it.
>
> I'm not sure I'm following you here.
>
> After the hotmovable memory configuration is detected it is possible to
> traverse reserved memblock areas and warn if some of them reside in the
> hotmovable memory.
>
Oh, sorry that I did not explain it accurately. Let use say a machine
with nodeA/B/C from low to high memory address. With top-down
allocation by default, at this point, memory will always be allocated
from nodeC. But it depends on machine whether nodeC is hotmovable or
not. The verification can pass on a machine with unmovable nodeC , but
fails on a machine with movable nodeC. It will be a probability issue.

Thanks

[...]