linux-kernel - Re: [PATCH v2] fs/hugetlbfs/inode.c: Ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min

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Message-ID: <dc4a8671-b8c2-484f-a83c-03bfc1fbe078@linux.ibm.com>
Date: Tue, 9 Jul 2024 19:14:38 +0530
From: Donet Tom <donettom@...ux.ibm.com>
To: Oscar Salvador <osalvador@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Muchun Song <muchun.song@...ux.dev>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Ritesh Harjani <ritesh.list@...il.com>,
        Mike Rapoport <rppt@...nel.org>, David Hildenbrand <david@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Tony Battersby
 <tonyb@...ernetics.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Alexei Starovoitov <ast@...nel.org>, Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v2] fs/hugetlbfs/inode.c: Ensure
 generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr


On 7/9/24 15:26, Oscar Salvador wrote:
> On Tue, Jul 09, 2024 at 04:21:22AM -0500, Donet Tom wrote:
>> generic_hugetlb_get_unmapped_area() was returning an address less
>> than mmap_min_addr if the mmap argument addr, after alignment, was
>> less than mmap_min_addr, causing mmap to fail.
>>
>> This is because current generic_hugetlb_get_unmapped_area() code does
>> not take into account mmap_min_addr.
>>
>> This patch ensures that generic_hugetlb_get_unmapped_area() always returns
>> an address that is greater than mmap_min_addr. Additionally, similar to
>> generic_get_unmapped_area(), vm_end_gap() checks are included to ensure
>> that the address is within the limit.
> Hi Donet,
>
> jfyi: I am already working on other parts of the kernel to avoid hugetlb code
> duplication vs mm core.
> I am also working on getting rid of hugetlb-unmapped_area specific code
> [1].
> I still need to perform some more tests but looks promising
> code-deletion-wise:
>
>    arch/parisc/mm/hugetlbpage.c     |  23 -------
>    arch/powerpc/mm/book3s64/slice.c |  49 ++++++++------
>    arch/s390/mm/hugetlbpage.c       |  84 ------------------------
>    arch/s390/mm/mmap.c              |  14 +++-
>    arch/sparc/kernel/sys_sparc_32.c |  16 +++--
>    arch/sparc/kernel/sys_sparc_64.c |  36 ++++++++---
>    arch/sparc/mm/hugetlbpage.c      | 108 -------------------------------
>    arch/x86/kernel/sys_x86_64.c     |  27 +++++---
>    arch/x86/mm/hugetlbpage.c        | 100 ----------------------------
>    fs/hugetlbfs/inode.c             |  97 ++-------------------------
>    include/linux/hugetlb.h          |  10 +++
>    mm/mmap.c                        |  25 ++++++-
>    12 files changed, 139 insertions(+), 450 deletions(-)
>
> I plan to post it in a day or two.
>
> [1] https://github.com/leberus/linux/tree/hugetlb-unmapped-area
Thank you Oscar.

The issue I am trying to fix will also get fixed by this new changes right.
So should we drop my patch or should we continue it?

-Donet