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 hCzXbRBA 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025-12-20 at 15:04 +1100, Hou Tao wrote... > From: Hou Tao > > Commit b7e282378773 has already changed the initial page refcount of > p2pdma page from one to zero, however, in p2pmem_alloc_mmap() it uses > "VM_WARN_ON_ONCE_PAGE(!page_ref_count(page))" to assert the initial page > refcount should not be zero and the following will be reported when > CONFIG_DEBUG_VM is enabled: > > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x380400000 > flags: 0x20000000002000(reserved|node=0|zone=4) > raw: 0020000000002000 ff1100015e3ab440 0000000000000000 0000000000000000 > raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: VM_WARN_ON_ONCE_PAGE(!page_ref_count(page)) > ------------[ cut here ]------------ > WARNING: CPU: 5 PID: 449 at drivers/pci/p2pdma.c:240 p2pmem_alloc_mmap+0x83a/0xa60 > > Fix by using "page_ref_count(page)" as the assertion condition. > > Fixes: b7e282378773 ("mm/mm_init: move p2pdma page refcount initialisation to p2pdma") Argh, thanks for fixing that. Reviewed-by: Alistair Popple > Signed-off-by: Hou Tao > --- > drivers/pci/p2pdma.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 218c1f5252b6..dd64ec830fdd 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -147,7 +147,7 @@ static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj, > * we have just allocated the page no one else should be > * using it. > */ > - VM_WARN_ON_ONCE_PAGE(!page_ref_count(page), page); > + VM_WARN_ON_ONCE_PAGE(page_ref_count(page), page); > set_page_count(page, 1); > ret = vm_insert_page(vma, vaddr, page); > if (ret) { > -- > 2.29.2 >