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charset=UTF-8 Subject: [PATCH v5 1/8] mm: fix stale ZONE_DEVICE refcount comment Message-Id: <20260701090553.62691-2-lizhe.67@bytedance.com> Mime-Version: 1.0 X-Stat-Signature: hhzq3t6ppnuhqxbbpu459m8fmzfpicz8 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 904A140005 X-HE-Tag: 1782896828-633031 X-HE-Meta: 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 iSlmZoug Bb0ya9KeFLTlBZSrLnRzna/y6W7SUBPAuJIB56CmDJQRz2UgWqoJF34SxKPSitG2+dytNc8GAxo7ljhZTQh4l4/ZRYQ3FkdVheqTlHAoWkznbDheqxsN9h2LCASX79h3dufkNTGxK2Z374JS4gIDnB/DtbqOSZVjNt2Yagjlo4BFs6CD0ZHuco640rCX8oweJuKDDhHikChlHQ0YS1unzIWzCMTq4vGTORszKLHNbzzLP6CfbmdjI2NboQs0NKPGIos71/TKTc+wIGwxhHOKr6FCoaGsTFjv9lGMYyW51Lj5q3BQBbu6zCor2fQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The comment in __init_zone_device_page() still uses the old MEMORY_TYPE_* names and implies that FS_DAX pages regain a refcount of 1 in the free path. That no longer matches the code. Update the comment to describe the current policy correctly: MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free path, while the remaining ZONE_DEVICE types start from 0 here and raise the count again when the allocator or driver hands the page out. No functional change intended. Signed-off-by: Li Zhe --- mm/mm_init.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 0f64909e8d20..95808ab5cfdb 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1030,13 +1030,9 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, page->zone_device_data = NULL; /* - * ZONE_DEVICE pages other than MEMORY_TYPE_GENERIC are released - * directly to the driver page allocator which will set the page count - * to 1 when allocating the page. - * - * MEMORY_TYPE_GENERIC and MEMORY_TYPE_FS_DAX pages automatically have - * their refcount reset to one whenever they are freed (ie. after - * their refcount drops to 0). + * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free + * path. The remaining ZONE_DEVICE types start from 0 here and raise + * the count again when the allocator or driver hands the page out. */ switch (pgmap->type) { case MEMORY_DEVICE_FS_DAX: -- 2.20.1