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From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
	"Liam R . Howlett" <Liam.Howlett@oracle.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	David Hildenbrand <david@redhat.com>,
	Pedro Falcato <pfalcato@suse.de>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 01/10] mm/mremap: introduce more mergeable mremap via MREMAP_RELOCATE_ANON
Date: Sat, 3 May 2025 15:29:08 +0100	[thread overview]
Message-ID: <dd10778d-3721-44da-8c7d-10d94378777f@lucifer.local> (raw)
In-Reply-To: <fb53f16c-9386-4b83-9696-1ab51f03fe54@lucifer.local>

OK have dug into this some more with a drgn script to read actual kernel
metadata state and it's simpler than I thought - the root anon_vma is
self-childed, but descendent anon_vma's are not.

We can correct this with a anon_vma->root == anon_vma check. I believe
we're probably safe with anon_vma reuse, because in that instance the
anon_vma would not be mapped a shared folio.

However, to be safe, I will check this, and I as I said previously, I will
add a number of tests explicitly tested forking scenarios.

The respin should have this fully addressed.

Thanks, Lorenzo


  reply	other threads:[~2025-05-03 14:29 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-22  8:09 [RFC PATCH v2 00/10] " Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 01/10] " Lorenzo Stoakes
2025-04-30  0:47   ` Wei Yang
2025-04-30 12:50     ` Vlastimil Babka
2025-04-30 13:15     ` Lorenzo Stoakes
2025-04-30 15:41       ` Wei Yang
2025-04-30 16:07         ` Lorenzo Stoakes
2025-05-01  1:18           ` Wei Yang
2025-05-01  9:27             ` Lorenzo Stoakes
2025-05-01 14:35               ` Wei Yang
2025-05-01 14:38                 ` Lorenzo Stoakes
2025-05-03 14:29                   ` Lorenzo Stoakes [this message]
2025-05-03 17:50                     ` Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 02/10] mm/mremap: add MREMAP_MUST_RELOCATE_ANON Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 03/10] mm/mremap: add MREMAP[_MUST]_RELOCATE_ANON support for large folios Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 04/10] tools UAPI: Update copy of linux/mman.h from the kernel sources Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 05/10] tools/testing/selftests: add sys_mremap() helper to vm_util.h Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 06/10] tools/testing/selftests: add mremap() cases that merge normally Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 07/10] tools/testing/selftests: add MREMAP_RELOCATE_ANON merge test cases Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 08/10] tools/testing/selftests: expand mremap() tests for MREMAP_RELOCATE_ANON Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 09/10] tools/testing/selftests: have CoW self test use MREMAP_RELOCATE_ANON Lorenzo Stoakes
2025-04-22  8:09 ` [RFC PATCH v2 10/10] tools/testing/selftests: test relocate anon in split huge page test Lorenzo Stoakes

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