Re: [PATCH gmem FIXUP] mm, compaction: make testing mapping_unmovable() safe
From: Matthew Wilcox <willy@infradead.org>
Date: 2023-09-02 13:59:57
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linuxppc-dev, lkml
On Fri, Sep 01, 2023 at 10:20:26AM +0200, 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. Also incorporate comment update suggested by Matthew.
In the meantime, 866ff80176aa went upstream earlier this merge window, so it's going to have some conflicts.