CVE-2026-98223

Summary

In the Linux kernel, the following vulnerability has been resolved:

mm: filemap: retain mapped dropbehind folios

Fault-around can map ready dropbehind folios without going through the normal page-cache lookup that clears dropbehind. A mapping represents a competing cached user, so retain the folio instead of forcibly unmapping it when writeback completes.

For a mapped folio, folio_unmap_invalidate() can call unmap_mapping_folio(), which takes i_mmap_rwsem and may sleep. Retaining mapped folios avoids this path when folio_end_dropbehind() runs in non-preemptible task context.

Tal was able to trigger a sleeping-in-atomic warning due to this [1].

Unmapped dropbehind folios continue through the existing invalidation path.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/2897601dffe576fcd87a4259102f41f7fb0cbfc8
• https://git.kernel.org/stable/c/77c0fade37c80e8aa16ac048a9828249055e3f66
• https://git.kernel.org/stable/c/848d2ce2fce15fbdc083fbf9691bfa72911033c4

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