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Howlett" , Andrew Morton References: <20261009-lazyfree-stable-fix-v1-1-70997958ef8d@nvidia.com> From: Lance Yang In-Reply-To: <20261009-lazyfree-stable-fix-v1-1-70997958ef8d@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 3p77i9fp3xize6fh93fcxnsm9rshhmqt X-Rspamd-Queue-Id: 8F41E1C0005 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1791599302-92062 X-HE-Meta: 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 rPNpHjrc ZEPwDskmSZxJM7uzDO7PYjsVYZ9OaFNWijxfYG1d/h6Tli9Tss8kclL1het9kNBvwd+IGcWkBCyLKYqCbh1N5Zr3d4B1qP6+Nnkw3tvRcOhC3H5k56KwVCZuMpd6nfG0dg1/fxj3mgC+nW3FrBytyxtYHusAr0GcLdt16rVYo4+8RoLENSQ0H6//BUiuOraZaZL6o1W9IVASWBx6l9KStMdfDGAMCh9KzHQXsBkPNG/cmSOSVX9MviND1Tf5sbCOl8KLRcu+uaD32EfsIbCQWK7pEwfOJdE7YiyLQzPj846NuECn1kVpBOho6mgFgH2gsnvwT3IixQqyuf7JoIbo9ANl5WcmqKSSQkSuN Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026/10/10 10:08, Zi Yan wrote: > __discard_anon_folio_pmd_locked() clears a lazyfree THP PMD before it knows > whether the folio can be discarded, and restores it if the folio was > redirtied or has extra references. A concurrent munmap() or > MREMAP_DONTUNMAP skips the temporary none PMD and unlinks the VMA from its > anon_vma, so the folio stays mapped after the anon_vma is freed and a later > rmap walk uses the freed anon_vma. > > Using an invalidated PMD instead of a cleared one requires additional arch > code fixes. Instead, disable the PMD level discard of lazyfree THPs, as > before commit 735ecdfaf4e8 ("mm/vmscan: avoid split lazyfree THP during > shrink_folio_list()"). > > Fixes: 735ecdfaf4e8 ("mm/vmscan: avoid split lazyfree THP during shrink_folio_list()") > Reported-by: Kyle Zeng > Closes: https://lore.kernel.org/r/20261009165214.40212-2-kylebot@openai.com > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Zi Yan > --- LGTM! Reviewed-by: Lance Yang