Hi, On 11/03/2025 09:34, Huan Yang wrote: > Hi Christoph and Ryan, > > Can you help us check vmap_pfn's pfn check is right? Did here mischecked pfn_valid? I'm no expert on this piece of code, but I believe pfn_valid() is checking to see if a pfn is valid *memory*. i.e. does it have a corresponding struct page? I'm guessing that vmap_pfn() is only intended to be used for non-memory pfns, e.g. mmio regions. You probably want either vmap() or vm_map_ram()? Thanks, Ryan > > Thank you. > > 在 2025/3/11 17:02, Bingbu Cao 写道: >> Christoph and Ryan, >> >> Could you help check this? Thanks. >> >> On 3/11/25 4:54 PM, Huan Yang wrote: >>> 在 2025/3/11 16:42, Bingbu Cao 写道: >>>> [You don't often get email from bingbu.cao@xxxxxxxxxxxxxxx. Learn why this >>>> is important at https://aka.ms/LearnAboutSenderIdentification ] >>>> >>>> Huan, >>>> >>>> Thanks for your response. >>>> >>>> On 3/11/25 3:12 PM, Huan Yang wrote: >>>>> 在 2025/3/11 14:40, Bingbu Cao 写道: >>>>>> [You don't often get email from bingbu.cao@xxxxxxxxxxxxxxx. Learn why this >>>>>> is important at https://aka.ms/LearnAboutSenderIdentification ] >>>>>> >>>>>> Huan Yang and Vivek, >>>>>> >>>>>> I am trying to use udmabuf for my test, and I cannot vmap the udmabuf >>>>>> buffers now. vmap_pfn_apply() will report a warning to complain that >>>>>> the pfns are invalid. >>>>>> I dump the pfn numbers as below: >>>>>> [ 3365.399641] pg[0] pfn 1148695 >>>>>> [ 3365.399642] pg[1] pfn 1145057 >>>>>> [ 3365.399642] pg[2] pfn 1134070 >>>>>> [ 3365.399643] pg[3] pfn 1148700 >>>>>> [ 3365.399643] pg[4] pfn 1144871 >>>>>> [ 3365.399643] pg[5] pfn 1408686 >>>>>> [ 3365.399643] pg[6] pfn 1408683 >>>>>> ... >>>>>> [ 3365.399660] WARNING: CPU: 3 PID: 2772 at mm/vmalloc.c:3489 >>>>>> vmap_pfn_apply+0xb7/0xd0 >>>>>> [ 3365.399667] Modules linked in:... >>>>>> [ 3365.399750] CPU: 3 UID: 0 PID: 2772 Comm: drm-test Not tainted 6.13.0- >>>>>> rc2-rvp #845 >>>>>> [ 3365.399752] Hardware name: Intel Corporation Client Platform/xxxx, BIOS >>>>>> xxxFWI1.R00.3221.D83.2408120121 08/12/2024 >>>>>> [ 3365.399753] RIP: 0010:vmap_pfn_apply+0xb7/0xd0 >>>>>> [ 3365.399755] Code: 5b 41 5c 41 5d 5d c3 cc cc cc cc 48 21 c3 eb d1 48 21 >>>>>> c3 48 23 3d 31 c0 26 02 eb c5 48 c7 c7 c4 3c 20 a8 e8 5b c0 d8 ff eb 8a >>>>>> <0f> 0b b8 ea ff ff ff 5b 41 5c 41 5d 5d c3 cc cc cc cc 0f 1f 80 00 >>>>>> [ 3365.399756] RSP: 0018:ffffb9b50c32fad0 EFLAGS: 00010202 >>>>>> [ 3365.399757] RAX: 0000000000000001 RBX: 0000000000118717 RCX: >>>>>> 0000000000000000 >>>>>> [ 3365.399758] RDX: 0000000080000000 RSI: ffffb9b50c358000 RDI: >>>>>> 00000000ffffffff >>>>>> [ 3365.399758] RBP: ffffb9b50c32fae8 R08: ffffb9b50c32fbd0 R09: >>>>>> 0000000000000001 >>>>>> [ 3365.399759] R10: ffff941602479288 R11: 0000000000000000 R12: >>>>>> ffffb9b50c32fbd0 >>>>>> [ 3365.399759] R13: ffff941618665ac0 R14: ffffb9b50c358000 R15: >>>>>> ffff941618665ac8 >>>>>> [ 3365.399760] FS: 00007ff9e9ddd740(0000) GS:ffff94196f780000(0000) >>>>>> knlGS:0000000000000000 >>>>>> [ 3365.399760] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>> [ 3365.399761] CR2: 000055fda5dc69d9 CR3: 00000001544de003 CR4: >>>>>> 0000000000f72ef0 >>>>>> [ 3365.399762] DR0: 0000000000000000 DR1: 0000000000000000 DR2: >>>>>> 0000000000000000 >>>>>> [ 3365.399762] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: >>>>>> 0000000000000400 >>>>>> [ 3365.399763] PKRU: 55555554 >>>>>> [ 3365.399763] Call Trace: >>>>>> [ 3365.399765] <TASK> >>>>>> [ 3365.399769] ? show_regs+0x6d/0x80 >>>>>> [ 3365.399773] ? __warn+0x97/0x160 >>>>>> [ 3365.399777] ? vmap_pfn_apply+0xb7/0xd0 >>>>>> [ 3365.399777] ? report_bug+0x1ec/0x240 >>>>>> [ 3365.399782] ? handle_bug+0x63/0xa0 >>>>>> [ 3365.399784] ? exc_invalid_op+0x1d/0x80 >>>>>> [ 3365.399785] ? asm_exc_invalid_op+0x1f/0x30 >>>>>> [ 3365.399790] ? vmap_pfn_apply+0xb7/0xd0 >>>>>> [ 3365.399791] __apply_to_page_range+0x522/0x8a0 >>>>>> [ 3365.399794] ? __pfx_vmap_pfn_apply+0x10/0x10 >>>>>> [ 3365.399795] apply_to_page_range+0x18/0x20 >>>>>> [ 3365.399796] vmap_pfn+0x77/0xd0 >>>>>> [ 3365.399797] vmap_udmabuf+0xc5/0x110 >>>>>> [ 3365.399802] dma_buf_vmap+0x96/0x130 >>>>>> >>>>>> I did an experiment to revert 18d7de823b7150344d242c3677e65d68c5271b04, >>>>>> then I can vmap the pages. Could you help what's wrong with that? >>>>> Sorry for that, as I reviewed pfn_valid, that's someting wired: >>>>> >>>>> /** >>>>> * pfn_valid - check if there is a valid memory map entry for a PFN >>>>> * @pfn: the page frame number to check >>>>> * >>>>> * Check if there is a valid memory map entry aka struct page for the @pfn. >>>>> * Note, that availability of the memory map entry does not imply that >>>>> * there is actual usable memory at that @pfn. The struct page may >>>>> * represent a hole or an unusable page frame. >>>>> * >>>>> * Return: 1 for PFNs that have memory map entries and 0 otherwise >>>>> */ >>>>> >>>>> So, if pfn valid, it's return 1, else 0. So mean, only 1 is a valid pfn. >>>>> But vmap_pfn_apply in there: >>>>> >>>>> static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private) >>>>> { >>>>> struct vmap_pfn_data *data = private; >>>>> unsigned long pfn = data->pfns[data->idx]; >>>>> pte_t ptent; >>>>> >>>>> if (WARN_ON_ONCE(pfn_valid(pfn))) >>>>> return -EINVAL; >>>>> >>>>> ptent = pte_mkspecial(pfn_pte(pfn, data->prot)); >>>>> set_pte_at(&init_mm, addr, pte, ptent); >>>>> >>>>> data->idx++; >>>>> return 0; >>>>> } >>>>> >>>>> Do it give a wrong check? maybe should fix by: >>>> I guess not, it looks more like warning when you trying to vmap a >>>> pfn which already took a valid entry in pte. >>> No, I think here check need pfn is valid, then can set it. If a pfn is >>> invalid, why we set it in PTE? >>> >>> Also, I can't make sure. >>> >>> BTW, can you fix it then retest? >>> >>> Thank you. >>> >>>> However, the MM code is so complex for me, just my guess. :) >>>> >>>>> static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private) >>>>> { >>>>> struct vmap_pfn_data *data = private; >>>>> unsigned long pfn = data->pfns[data->idx]; >>>>> pte_t ptent; >>>>> >>>>> - if (WARN_ON_ONCE(pfn_valid(pfn))) >>>>> + if (WARN_ON_ONCE(!pfn_valid(pfn))) >>>>> return -EINVAL; >>>>> >>>>> ptent = pte_mkspecial(pfn_pte(pfn, data->prot)); >>>>> set_pte_at(&init_mm, addr, pte, ptent); >>>>> >>>>> data->idx++; >>>>> return 0; >>>>> } >>>>> >>>>> Please help me check it, also, you can apply this and then check it.:) >>>>> >>>>>> -- >>>>>> Best regards, >>>>>> Bingbu Cao >>>> -- >>>> Best regards, >>>> Bingbu Cao
