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WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <84282e55-519c-0e17-30c5-b6de54d1001c@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.30.204] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 3D5798001D X-Rspam-User: X-Stat-Signature: hefi1ohbskj8gexrucg95hjksp31w5pz X-Rspamd-Server: rspam03 X-HE-Tag: 1695200350-328401 X-HE-Meta: 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 bfZ2fSOJ 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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: On 2023/9/15 16:28, Jesper Dangaard Brouer wrote: > Hi Lin, > > This looks reasonable, but given you are changing struct-page > (include/linux/mm_types.h) we need to MM-list . > Also Cc Wilcox. > > I think it was Ilias and Duyck that validated the assumptions, last time > this patch was discussed. Thus I want to see their review before this is > applied. FWIW, PAGE_SIZE aligned buffer being PAGE_SIZE aligned in DMA is validated by Duyck: https://lore.kernel.org/all/CAKgT0UfeUAUQpEffxnkc+gzXsjOrHkuMgxU_Aw0VXSJYKzaovQ@mail.gmail.com/ And I had done researching to find out there seems to be no combination of the above arch with an address space >16TB: https://lore.kernel.org/all/2b570282-24f8-f23b-1ff7-ad836794baa9@huawei.com/ > > -Jesper > > On 12/09/2023 10.31, Yunsheng Lin wrote: >> Currently page_pool_alloc_frag() is not supported in 32-bit >> arch with 64-bit DMA because of the overlap issue between >> pp_frag_count and dma_addr_upper in 'struct page' for those >> arches, which seems to be quite common, see [1], which means >> driver may need to handle it when using frag API. >> >> It is assumed that the combination of the above arch with an >> address space >16TB does not exist, as all those arches have >> 64b equivalent, it seems logical to use the 64b version for a >> system with a large address space. It is also assumed that dma >> address is page aligned when we are dma mapping a page aliged >> buffer, see [2]. >> >> That means we're storing 12 bits of 0 at the lower end for a >> dma address, we can reuse those bits for the above arches to >> support 32b+12b, which is 16TB of memory. >> >> If we make a wrong assumption, a warning is emitted so that >> user can report to us. >> >> 1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.com/ >> 2. https://lore.kernel.org/all/20230818145145.4b357c89@kernel.org/ >> >> Signed-off-by: Jakub Kicinski >> Signed-off-by: Yunsheng Lin >> CC: Lorenzo Bianconi >> CC: Alexander Duyck >> CC: Liang Chen >> CC: Alexander Lobakin >> CC: Guillaume Tucker >> --- >> include/linux/mm_types.h | 13 +------------ >> include/net/page_pool/helpers.h | 20 ++++++++++++++------ >> net/core/page_pool.c | 14 +++++++++----- >> 3 files changed, 24 insertions(+), 23 deletions(-) >> >> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h >> index 36c5b43999e6..74b49c4c7a52 100644 >> --- a/include/linux/mm_types.h >> +++ b/include/linux/mm_types.h >> @@ -125,18 +125,7 @@ struct page { >> struct page_pool *pp; >> unsigned long _pp_mapping_pad; >> unsigned long dma_addr; >> - union { >> - /** >> - * dma_addr_upper: might require a 64-bit >> - * value on 32-bit architectures. >> - */ >> - unsigned long dma_addr_upper; >> - /** >> - * For frag page support, not supported in >> - * 32-bit architectures with 64-bit DMA. >> - */ >> - atomic_long_t pp_frag_count; >> - }; >> + atomic_long_t pp_frag_count; >> }; >> struct { /* Tail pages of compound page */ >> unsigned long compound_head; /* Bit zero is set */ >> diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h >> index 94231533a369..8e1c85de4995 100644 >> --- a/include/net/page_pool/helpers.h >> +++ b/include/net/page_pool/helpers.h >> @@ -197,7 +197,7 @@ static inline void page_pool_recycle_direct(struct page_pool *pool, >> page_pool_put_full_page(pool, page, true); >> } >> -#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ >> +#define PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA \ >> (sizeof(dma_addr_t) > sizeof(unsigned long)) >> /** >> @@ -211,17 +211,25 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) >> { >> dma_addr_t ret = page->dma_addr; >> - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) >> - ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16; >> + if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) >> + ret <<= PAGE_SHIFT; >> return ret; >> } >> -static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr) >> +static inline bool page_pool_set_dma_addr(struct page *page, dma_addr_t addr) >> { >> + if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) { >> + page->dma_addr = addr >> PAGE_SHIFT; >> + >> + /* We assume page alignment to shave off bottom bits, >> + * if this "compression" doesn't work we need to drop. >> + */ >> + return addr != (dma_addr_t)page->dma_addr << PAGE_SHIFT; >> + } >> + >> page->dma_addr = addr; >> - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) >> - page->dma_addr_upper = upper_32_bits(addr); >> + return false; >> } >> static inline bool page_pool_put(struct page_pool *pool) >> diff --git a/net/core/page_pool.c b/net/core/page_pool.c >> index 77cb75e63aca..8a9868ea5067 100644 >> --- a/net/core/page_pool.c >> +++ b/net/core/page_pool.c >> @@ -211,10 +211,6 @@ static int page_pool_init(struct page_pool *pool, >> */ >> } >> - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT && >> - pool->p.flags & PP_FLAG_PAGE_FRAG) >> - return -EINVAL; >> - >> #ifdef CONFIG_PAGE_POOL_STATS >> pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats); >> if (!pool->recycle_stats) >> @@ -359,12 +355,20 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page) >> if (dma_mapping_error(pool->p.dev, dma)) >> return false; >> - page_pool_set_dma_addr(page, dma); >> + if (page_pool_set_dma_addr(page, dma)) >> + goto unmap_failed; >> if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) >> page_pool_dma_sync_for_device(pool, page, pool->p.max_len); >> return true; >> + >> +unmap_failed: >> + WARN_ON_ONCE("unexpected DMA address, please report to netdev@"); >> + dma_unmap_page_attrs(pool->p.dev, dma, >> + PAGE_SIZE << pool->p.order, pool->p.dma_dir, >> + DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING); >> + return false; >> } >> static void page_pool_set_pp_info(struct page_pool *pool, > > . >