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From: Florian Weimer <fweimer@redhat.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-mm <linux-mm@kvack.org>
Subject: Re: POWER: Unexpected fault when writing to brk-allocated memory
Date: Mon, 6 Nov 2017 09:10:10 +0100	[thread overview]
Message-ID: <fed9e04f-e69d-df8d-a930-2f71d7814a64@redhat.com> (raw)
In-Reply-To: <871slcszfl.fsf@linux.vnet.ibm.com>

On 11/06/2017 07:18 AM, Aneesh Kumar K.V wrote:
> We should not return that address, unless we requested with a hint value
> of > 128TB. IIRC we discussed this early during the mmap interface
> change and said, we will return an address > 128T only if the hint
> address is above 128TB (not hint addr + length). I am not sure why
> we are finding us returning and address > 128TB with paca limit set to
> 128TB?

See the memory maps I posted.  I think it was not anticipated that the 
heap could be near the 128 TiB limit because it is placed next to the 
initially mapped object.

I think this could become worse once we have static PIE support because 
static PIE binaries likely have the same memory layout.  (Ordinary PIE 
does not.)

Thanks,
Florian

WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fweimer@redhat.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-mm <linux-mm@kvack.org>
Subject: Re: POWER: Unexpected fault when writing to brk-allocated memory
Date: Mon, 6 Nov 2017 09:10:10 +0100	[thread overview]
Message-ID: <fed9e04f-e69d-df8d-a930-2f71d7814a64@redhat.com> (raw)
In-Reply-To: <871slcszfl.fsf@linux.vnet.ibm.com>

On 11/06/2017 07:18 AM, Aneesh Kumar K.V wrote:
> We should not return that address, unless we requested with a hint value
> of > 128TB. IIRC we discussed this early during the mmap interface
> change and said, we will return an address > 128T only if the hint
> address is above 128TB (not hint addr + length). I am not sure why
> we are finding us returning and address > 128TB with paca limit set to
> 128TB?

See the memory maps I posted.  I think it was not anticipated that the 
heap could be near the 128 TiB limit because it is placed next to the 
initially mapped object.

I think this could become worse once we have static PIE support because 
static PIE binaries likely have the same memory layout.  (Ordinary PIE 
does not.)

Thanks,
Florian

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  parent reply	other threads:[~2017-11-06  8:10 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-03 17:05 POWER: Unexpected fault when writing to brk-allocated memory Florian Weimer
2017-11-03 17:05 ` Florian Weimer
2017-11-05 12:18 ` Nicholas Piggin
2017-11-05 12:18   ` Nicholas Piggin
2017-11-05 12:35   ` Florian Weimer
2017-11-05 12:54     ` Nicholas Piggin
2017-11-05 12:54       ` Nicholas Piggin
2017-11-05 14:50   ` Florian Weimer
2017-11-05 14:50     ` Florian Weimer
2017-11-06  6:18   ` Aneesh Kumar K.V
2017-11-06  6:18     ` Aneesh Kumar K.V
2017-11-06  6:47     ` Nicholas Piggin
2017-11-06  6:47       ` Nicholas Piggin
2017-11-06  8:11       ` Florian Weimer
2017-11-06  8:11         ` Florian Weimer
2017-11-06  8:25         ` Nicholas Piggin
2017-11-06  8:25           ` Nicholas Piggin
2017-11-06  8:30           ` Aneesh Kumar K.V
2017-11-06  8:30             ` Aneesh Kumar K.V
2017-11-06  8:32             ` Florian Weimer
2017-11-06  8:32               ` Florian Weimer
2017-11-06 10:20               ` Nicholas Piggin
2017-11-06 10:20                 ` Nicholas Piggin
2017-11-07  5:07               ` Nicholas Piggin
2017-11-07  5:07                 ` Nicholas Piggin
2017-11-07  8:15                 ` Florian Weimer
2017-11-07  8:15                   ` Florian Weimer
2017-11-07  9:24                   ` Nicholas Piggin
2017-11-07  9:24                     ` Nicholas Piggin
2017-11-07 11:16                   ` Kirill A. Shutemov
2017-11-07 11:16                     ` Kirill A. Shutemov
2017-11-07 11:15                 ` Kirill A. Shutemov
2017-11-07 11:15                   ` Kirill A. Shutemov
2017-11-07 11:26                   ` Florian Weimer
2017-11-07 11:26                     ` Florian Weimer
2017-11-07 11:44                     ` Kirill A. Shutemov
2017-11-07 11:44                       ` Kirill A. Shutemov
2017-11-07 13:05                       ` Florian Weimer
2017-11-07 13:16                         ` Kirill A. Shutemov
2017-11-07 13:16                           ` Kirill A. Shutemov
2017-11-08  6:08                           ` Michael Ellerman
2017-11-08  6:08                             ` Michael Ellerman
2017-11-08  6:18                             ` Florian Weimer
2017-11-08  6:18                               ` Florian Weimer
2017-11-07 11:56                   ` Nicholas Piggin
2017-11-07 11:56                     ` Nicholas Piggin
2017-11-07 12:28                     ` Kirill A. Shutemov
2017-11-07 12:28                       ` Kirill A. Shutemov
2017-11-07 13:33                       ` Nicholas Piggin
2017-11-07 13:33                         ` Nicholas Piggin
2017-11-07 13:45                         ` Aneesh Kumar K.V
2017-11-07 13:45                           ` Aneesh Kumar K.V
2017-11-07 14:01                           ` Kirill A. Shutemov
2017-11-07 14:01                             ` Kirill A. Shutemov
2017-11-09 17:15                             ` Nicholas Piggin
2017-11-09 17:15                               ` Nicholas Piggin
2017-11-09 19:44                               ` Matthew Wilcox
2017-11-09 19:44                                 ` Matthew Wilcox
2017-11-10  1:26                                 ` Nicholas Piggin
2017-11-10  1:26                                   ` Nicholas Piggin
2017-11-10 12:08                                 ` David Laight
2017-11-10 12:08                                   ` David Laight
2017-11-11 10:30                                   ` Nicholas Piggin
2017-11-11 10:30                                     ` Nicholas Piggin
2017-11-08  4:56                           ` Michael Ellerman
2017-11-08  4:56                             ` Michael Ellerman
2017-11-08  8:30                             ` Kirill A. Shutemov
2017-11-08  8:30                               ` Kirill A. Shutemov
2017-11-06  8:10     ` Florian Weimer [this message]
2017-11-06  8:10       ` Florian Weimer

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