From: Sean Christopherson <seanjc@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: ackerleytng@google.com, akpm@linux-foundation.org,
anup@brainfault.org, aou@eecs.berkeley.edu,
chao.p.peng@linux.intel.com, chenhuacai@kernel.org,
david@redhat.com, isaku.yamahata@gmail.com, jarkko@kernel.org,
jmorris@namei.org, kirill.shutemov@linux.intel.com,
kvm-riscv@lists.infradead.org, kvm@vger.kernel.org,
kvmarm@lists.linux.dev, liam.merwick@oracle.com,
linux-arm-kernel@lists.infradead.org,
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pbonzini@redhat.com, qperret@google.com, serge@hallyn.com,
tabba@google.com, vannapurve@google.com, wei.w.wang@intel.com,
willy@infradead.org, yu.c.zhang@linux.intel.com
Subject: Re: [PATCH gmem FIXUP] mm, compaction: make testing mapping_unmovable() safe
Date: Tue, 5 Sep 2023 16:56:31 -0700 [thread overview]
Message-ID: <ZPfAL0D95AwXD9tg@google.com> (raw)
In-Reply-To: <20230901082025.20548-2-vbabka@suse.cz>
On Fri, Sep 01, 2023, Vlastimil Babka wrote:
> As Kirill pointed out, mapping can be removed under us due to
> truncation. Test it under folio lock as already done for the async
> compaction / dirty folio case. To prevent locking every folio with
> mapping to do the test, do it only for unevictable folios, as we can
> expect the unmovable mapping folios are also unevictable - it is the
> case for guest memfd folios.
Rather than expect/assume that unmovable mappings are always unevictable, how about
requiring that? E.g. either through a VM_WARN_ON in mapping_set_unmovable(), or by
simply having that helper forcefully set AS_UNEVICTABLE as well.
next prev parent reply other threads:[~2023-09-05 23:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-01 8:20 [PATCH gmem FIXUP] mm, compaction: make testing mapping_unmovable() safe Vlastimil Babka
2023-09-01 21:05 ` kirill.shutemov
2023-09-02 13:59 ` Matthew Wilcox
2023-09-05 23:56 ` Sean Christopherson [this message]
2023-09-06 8:00 ` Vlastimil Babka
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