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

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Message-ID: <ed11cb24-acc6-4d1d-a559-0708cdc4786b@linux.ibm.com>
Date: Fri, 5 Jul 2024 22:18:01 +0530
From: Donet Tom <donettom@...ux.ibm.com>
To: "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Muchun Song <muchun.song@...ux.dev>, 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>,
        jj@...ck.fi.intel.com
Subject: Re: [PATCH] fs/hugetlbfs/inode.c: Ensure
 generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr


On 7/5/24 17:53, Kirill A . Shutemov wrote:
> On Fri, Jul 05, 2024 at 02:11:50AM -0500, Donet Tom wrote:
>> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
>> index 412f295acebe..428fd2f0e4c4 100644
>> --- a/fs/hugetlbfs/inode.c
>> +++ b/fs/hugetlbfs/inode.c
>> @@ -228,7 +228,7 @@ generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
>>   
>>   	if (len & ~huge_page_mask(h))
>>   		return -EINVAL;
>> -	if (len > TASK_SIZE)
>> +	if (len > mmap_end - mmap_min_addr)
>>   		return -ENOMEM;
>>   
>>   	if (flags & MAP_FIXED) {
>> @@ -240,7 +240,7 @@ generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
>>   	if (addr) {
>>   		addr = ALIGN(addr, huge_page_size(h));
>>   		vma = find_vma(mm, addr);
>> -		if (mmap_end - len >= addr &&
>> +		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
>>   		    (!vma || addr + len <= vm_start_gap(vma)))
>>   			return addr;
>>   	}
> There's more difference with generic_get_unmapped_area() than what you are
> fixing. I think we also need vm_end_gap() here.
Thank you for your comment. I will add this change and send V2.

-Donet
>
> Hugetlb code duplication is annoying.
>