Re: [PATCH gmem FIXUP] mm, compaction: make testing mapping_unmovable() safe
From: Sean Christopherson <seanjc@google.com>
Date: 2023-09-05 23:56:42
Also in:
kvm, kvm-riscv, kvmarm, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linux-security-module, linuxppc-dev, lkml
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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel