linux-kernel - Re: [PATCH 0/4] mm: permit guard regions for file-backed/shmem mappings

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Message-ID: <ac7d3b7c-7b36-47d2-be59-c1b6e0fa2d38@redhat.com>
Date: Tue, 18 Feb 2025 18:31:52 +0100
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Suren Baghdasaryan <surenb@...gle.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 Matthew Wilcox <willy@...radead.org>, "Paul E . McKenney"
 <paulmck@...nel.org>, Jann Horn <jannh@...gle.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
 linux-kselftest@...r.kernel.org, linux-api@...r.kernel.org,
 John Hubbard <jhubbard@...dia.com>, Juan Yescas <jyescas@...gle.com>,
 Kalesh Singh <kaleshsingh@...gle.com>
Subject: Re: [PATCH 0/4] mm: permit guard regions for file-backed/shmem
 mappings

>> See mlock2();
>>
>> SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
>> {
>> 	vm_flags_t vm_flags = VM_LOCKED;
>>
>> 	if (flags & ~MLOCK_ONFAULT)
>> 		return -EINVAL;
>>
>> 	if (flags & MLOCK_ONFAULT)
>> 		vm_flags |= VM_LOCKONFAULT;
>>
>> 	return do_mlock(start, len, vm_flags);
>> }
>>
>>
>> VM_LOCKONFAULT always as VM_LOCKED set as well.
> 
> OK cool, that makes sense.
> 
> As with much kernel stuff, I knew this in the past. Then I forgot. Then I knew
> again, then... :P if only somebody would write it down in a book...

And if there would be such a book in the makings, I would consider 
hurrying up and preordering it ;)

-- 
Cheers,

David / dhildenb