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From: David Laight <David.Laight@ACULAB.COM>
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CC: "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>, "Guo
 Ren" <guoren@linux.alibaba.com>, "stable@vger.kernel.org"
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Subject: RE: [PATCH V2 2/4] riscv: mm: Fixup compat arch_get_mmap_end
Thread-Topic: [PATCH V2 2/4] riscv: mm: Fixup compat arch_get_mmap_end
Thread-Index: AQHaNCUDLOr76Y7kz0WYFR/4SG7VuLC1ATgA
Date: Fri, 22 Dec 2023 08:59:47 +0000
Message-ID: <367b05acb90d4a6e898dd34e4254b697@AcuMS.aculab.com>
References: <20231221154702.2267684-1-guoren@kernel.org>
 <20231221154702.2267684-3-guoren@kernel.org>
In-Reply-To: <20231221154702.2267684-3-guoren@kernel.org>
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From: guoren@kernel.org <guoren@kernel.org>
> Sent: 21 December 2023 15:47
>=20
> From: Guo Ren <guoren@linux.alibaba.com>
>=20
> When the task is in COMPAT mode, the arch_get_mmap_end should be 2GB,
> not TASK_SIZE_64. The TASK_SIZE has contained is_compat_mode()
> detection, so change the definition of STACK_TOP_MAX to TASK_SIZE
> directly.

Why 2G ?

IIRC for 32-bit native x86 the limit is 3G, but in compat mode
it is (just under) 4G.

There is a special mmap option (for programs like wine) to
limit mmap() to 2G.

=09David

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