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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org References: <20260327014255.2058916-1-ziy@nvidia.com> <20260327014255.2058916-3-ziy@nvidia.com> From: Baolin Wang In-Reply-To: <20260327014255.2058916-3-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 03AEF20007 X-Stat-Signature: ea73ndgz9u8gejkihitcd4yeegeymhsg X-HE-Tag: 1774604694-404981 X-HE-Meta: U2FsdGVkX18pVFxzDBCdfxOqEaiEcNFnIpnH8CljQSXfac5UejDymdOXG16uP1uyhQ5WfmVp8QjB1YCddi7gjAL+QUhCa1Zd8LSmJurLhJn9w7KqHBeJnJn5xmI0/TtGNQWSzBrS2Qsab3dGVlPf/zCtLXEx8eYR8PEsSuh5JHBdC3MYbHyqAQwYlbL3BQmS2vtZovl1Gp6oE8uKPMardlSeidM/+xSPMftMgGD9pXayDzjkjvRm9JWL/r2nHWy2Qo6rgSCVV856wLLTldzxi7Qan3TCv7rJX8lNS6t5Jzsr1OQCbWSYthL8Jv7Plder8vtxAsFjTjcSAP/wBdZSvZUmSVGgqCo28IJZotfhrfXdCQgWSKxUjqRrwZ/IjCcOxIxz5PxFeFQ5ubTZFpx/SHCLUFdp46g1l6grasqw+C/Gnhl6zaqXDXXh0+WxRFMwenIvixk2SqNiCPNkC8UHIjsWvUUrorRMMdqWlrzOmeqDhxOAHydbOpOEHjbYN5leN0+ux2/O7P5xCLz1390KB/3lFz6qxNL+0Jo5ShHN/Bms7dDVxoaxp9/zprLYiaEQ1Xvd5cFgv6Xq3yO68n6NQR4MD/SSvXVKmFCQact5itZrvGGCmqLZJaacMXEWyCo1HW1Vl7inKGqMYcbaYjIclN/Z7FnnWoEuCJupYvfRd+nL+wxS+gfzibwx2JeIBmecKV3SaF6i8a2Dw/R4rLPoymEC4pOLDxj32x+zzYY83RaeIcrm/GQokfrq6e0BPCGFgees6PH4tiU055or91NO0F8N09s3/8CebMkSBNbPenNSZ2A7FHhVfZxaCUZUurKrVBwi6CoAGVhNPXKmzI8SHFEVOrpSaWCFTkTac3ccOvecm4DP2JwdPRVfrc5euErp/o5nwkcE5Fp0mWmELIst23PPwkNNNe7qzJDCPZcSxnOH9TupMgZm2WhhT/CvrarBH4njToUtOeSqjpqTl9w Lvd5DZ+k 6zs9o8tAEd3Fvx9XGjs718SluJPBg7aLk4EgsNaVsn7Z5Wf4BgfVL0vTNf1JDypuH2zw+PCsq/sErZGikIFMQ+XepfRgu9JuRK+h2SW7ATWEnb1YWYKKdwjDm8BPVYFt05s2fbCjFFWaImGcpRIWyd5eYX9JItvjLMIHkV1B14FhIchwt9zIcLFmEWiGRPLJotAtFSZDco1o956kRsw1gvH2Y1PQDPldCX3n46+8gTjAHsHVnj8rO15OfYqzoSK132IC6ERrAfuhbUWFz2zxmoWSknEFxFPNqjK2wcN0rUHOzbZCDFNiUQ6uJP+J2Qh7CfVwoTf7BrMSihUbHXOo4Tn+hs4FOr42pyI/ntEuFnp6fjbl3JY0bgQIhIm/3XED2mq79 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/27/26 9:42 AM, Zi Yan wrote: > collapse_file() requires FSes supporting large folio with at least > PMD_ORDER, so replace the READ_ONLY_THP_FOR_FS check with that. shmem with > huge option turned on also sets large folio order on mapping, so the check > also applies to shmem. > > While at it, replace VM_BUG_ON with returning failure values. > > Signed-off-by: Zi Yan > --- > mm/khugepaged.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index d06d84219e1b..45b12ffb1550 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1899,8 +1899,11 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, > int nr_none = 0; > bool is_shmem = shmem_file(file); > > - VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); > - VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); > + /* "huge" shmem sets mapping folio order and passes the check below */ > + if (mapping_max_folio_order(mapping) < PMD_ORDER) > + return SCAN_FAIL; This is not true for anonymous shmem, since its large order allocation logic is similar to anonymous memory. That means it will not call mapping_set_large_folios() for anonymous shmem. So I think the check should be: if (!is_shmem && mapping_max_folio_order(mapping) < PMD_ORDER) return SCAN_FAIL;