From: David Hildenbrand <david@redhat.com>
To: Guillaume Morin <guillaume@morinfr.org>
Cc: oleg@redhat.com, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, muchun.song@linux.dev
Subject: Re: [RFC][PATCH] uprobe: support for private hugetlb mappings
Date: Tue, 30 Apr 2024 21:25:32 +0200 [thread overview]
Message-ID: <8a7b9e65-b073-4132-9680-efc2b3af6af0@redhat.com> (raw)
In-Reply-To: <ZiwGovSHiVCF7z6y@bender.morinfr.org>
On 26.04.24 21:55, Guillaume Morin wrote:
> On 26 Apr 9:19, David Hildenbrand wrote:
>> A couple of points:
>>
>> a) Don't use page_mapcount(). Either folio_mapcount(), but likely you want
>> to check PageAnonExclusive.
>>
>> b) If you're not following the can_follow_write_pte/_pmd model, you are
>> doing something wrong :)
>>
>> c) The code was heavily changed in mm/mm-unstable. It was merged with t
>> the common code.
>>
>> Likely, in mm/mm-unstable, the existing can_follow_write_pte and
>> can_follow_write_pmd checks will already cover what you want in most cases.
>>
>> We'd need a can_follow_write_pud() to cover follow_huge_pud() and
>> (unfortunately) something to handle follow_hugepd() as well similarly.
>>
>> Copy-pasting what we do in can_follow_write_pte() and adjusting for
>> different PTE types is the right thing to do. Maybe now it's time to factor
>> out the common checks into a separate helper.
>
> I tried to get the hugepd stuff right but this was the first I heard
> about it :-) Afaict follow_huge_pmd and friends were already DTRT
I'll have to have a closer look at some details (the hugepd writability
check looks a bit odd), but it's mostly what I would have expected!
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-04-30 19:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-19 18:37 [RFC][PATCH] uprobe: support for private hugetlb mappings Guillaume Morin
2024-04-22 9:39 ` David Hildenbrand
2024-04-22 18:11 ` Guillaume Morin
2024-04-22 18:59 ` David Hildenbrand
2024-04-22 20:53 ` Guillaume Morin
2024-04-24 20:09 ` David Hildenbrand
2024-04-24 20:44 ` Guillaume Morin
2024-04-24 21:00 ` David Hildenbrand
2024-04-25 15:19 ` Guillaume Morin
2024-04-25 15:42 ` David Hildenbrand
2024-04-25 19:56 ` David Hildenbrand
2024-04-26 0:09 ` Guillaume Morin
2024-04-26 7:19 ` David Hildenbrand
2024-04-26 19:55 ` Guillaume Morin
2024-04-30 15:22 ` Guillaume Morin
2024-04-30 18:21 ` David Hildenbrand
2024-04-30 18:58 ` Guillaume Morin
2024-04-30 19:25 ` David Hildenbrand [this message]
2024-05-02 3:59 ` Guillaume Morin
2024-05-16 17:44 ` Guillaume Morin
2024-05-16 19:52 ` David Hildenbrand
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