From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5F20C21A453 for ; Tue, 19 May 2026 05:10:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779167416; cv=none; b=PDSnj33mzBXZYWLeYTk5MIcvzAU8vhhmcvTDmdcIhDJGwoFMWkSiLo+gbcP3jZ6d0Jjr6ArV9mxzmGgc66YWePcAFjKUYdSeV9L0Jtt/196CofWxyxhxmtypcB1zE23/5cufp4I7AldKWdCRU/CkwhmWtuL/VxPsfU0ZjDitQlA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779167416; c=relaxed/simple; bh=W/vPzVKAT51UmEJ2dAG7p0cDx3NoxcWzZ6SLqrYYn2E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=On8TuAzdSYAM/vT/N+Cr+QeKaBglw5Zac59/wRVY+xQEcxQRMqVer/nRIguDCIy5L0bFB6JB8iYO+zSXvhMeQhIkCBO3Bt0L5gabNULbPSU0DmNcLUFCLO47p1MQQMlmzk7K8a59BrFeJ/keUwgB9EpSBiMAm3Q2hhOvCEsbWIw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-c45ff70000001609-7b-6a0bf0b0e439 Date: Tue, 19 May 2026 14:10:02 +0900 From: Byungchul Park To: Andrew Morton Cc: mm-commits@vger.kernel.org, ziy@nvidia.com, willy@infradead.org, vbabka@kernel.org, toke@redhat.com, tariqt@nvidia.com, surenb@google.com, sdf@fomichev.me, saeedm@nvidia.com, rppt@kernel.org, pabeni@redhat.com, mhocko@suse.com, mbloch@nvidia.com, ljs@kernel.org, liam@infradead.org, leon@kernel.org, kuba@kernel.org, john.fastabend@gmail.com, jackmanb@google.com, ilias.apalodimas@linaro.org, horms@kernel.org, hawk@kernel.org, harry@kernel.org, hannes@cmpxchg.org, edumazet@google.com, dtatulea@nvidia.com, david@kernel.org, davem@davemloft.net, baolin.wang@linux.alibaba.com, ast@kernel.org, asml.silence@gmail.com, kernel_team@skhynix.com Subject: Re: + revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type.patch added to mm-hotfixes-unstable branch Message-ID: <20260519051002.GA16061@system.software.com> References: <20260519003125.5006AC2BCB7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260519003125.5006AC2BCB7@smtp.kernel.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA03Se0hTcRQH8H733t3dLRfXafrLHsREAkF74B9HkPCvuEVP7I8ef9Ryl5yP KZuv9QBNyRJNM42cCyzMV+lsPicqNstnpRizVaapmUm+leE0NGdJ/vfhHM73nD8OQ0qXKQ9G qYrm1Sp5uIwWU+JJpyc+FTNbQw/0dbuC3vCCBn1pDYIF+xchrDa2ItB3J1MwVr2EwFQ/hmC0 dVgIz40n4OPnEgQNKbUkDGe005CevExCo31KCLfqignoqbkngOylZySUd5ppmBg5AjM5r0kY vBcIv+73CMDWNYHgtaGWAFvaYxosufUEPOjNp2EkeRBBb8swBXfGBylYXtTTkPdmQBi4l2uZ mCa5qpJPBGdt6iQ4k+6rkMs3xnCVxd6csfQuzfX3NdBc+6NlijMN+XPpSVM0N91koTlDlYXi 5o17Tm+7IA5Q8OHKWF69//Blccj7ygEUVR4X352dTSagl+dSkYjBrB8um02iNpxhKBA4TLFe eNyWQTpMs/uw1Wpftyvrg0vH6tcsZkg2V4B/lmeuD7uwN7Cp49m6JSzg/HfVtMPSNX/Tpfyr O+OO3O/rJllvbF0ZJ1IRs+aduGiFcZRFrD8usw4SDm9nPXFzTRvh2IXZHAYPJ/agv4fuwK+K rVQmYnWbYnWbYnX/Y/MRWYqkSlVshFwZ7ucbolUp432DIyOMaO0lCm/+vliH5nqCzIhlkMxJ ErgqDpUK5LEabYQZYYaUuUpWDKJQqUQh117j1ZGX1DHhvMaMdjKUzF1yyBankLJX5dF8GM9H 8eqNLsGIPBIQr5gQq5cC5gX+UwOcpuHsrGWoVu++4Bx0vv9hnkuGx9EK6aO3pzRd5pOLSd2j nonn26+8SU+Wxe2uU7cRI6IionW+V1GwEHm9ZO6Y/cGu/heh9i0d+qc2r5SZsNOrkKYNLrS4 5ZncphXPswprsjIbm2Ufjs+pftzWkjdzfpyZlFGaEPlBb1Ktkf8BPLt9FA4DAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA03Ra0hTYRwG8N5zzs7OVsvTtDoqCa1EErSUhL90wQrqRUrqUyFEjjrldC7Z 1NQuSBpaZGau0KUwqqUu22wzdZIS08wLXjBWs9LZNFQyFRLzEpqTor79eB6eTw9DSt2UH6NQ pfBqlVwpo8WUOGZPdkj19NqEXf1WAkrNVTSUGmsRzMx/EsJyYyuC0p4cCkZfLiCwNYwi+Nrq FsIzyzH48LESwavcOhLcBW005OcsktA4PymE6/UVBDSXtQugt/aOALQLBhJMHXYaJoYPw/T9 FhJcd6LgW2GvAGY7JxC0mOsImL1dRoOjpIGAoj49DcM5LgR9zW4K8sZdFCzOldLw8M2gMGor bp6YInFNZT+BnU0dBLbpBoRYb0nF1opgbDHepPHn969o3Fa8SGHbl0icnz1J46kmB40fj00T 2FzjoPAPS8Bxr1jx3nO8UpHGq3fujxPHd1sHUbLpUnqPVktmoRenbiERw7G7uQLzE4HHFBvI jc8WkB7TbBDndM6v2ocN4YyjDSsWMyRbIuDGTHcpT+HNXuFs7YZVS1jg9F0vaY+lKx7S5f7J N3DtJSOrJtlgzrk0TtxCzIr9ufIlxhOL2EjuudNFeLyR3ca9rn1L3EUS3X9r3X9r3b+1HpFG 5KNQpSXJFcqIUE1ifIZKkR569mKSBa08//Tqr8J6NPPuiB2xDJKtk0QtixOkAnmaJiPJjjiG lPlIlsyiBKnknDwjk1dfPKNOVfIaO/JnKNlmSfRJPk7KXpCn8Ik8n8yr/7YEI/LLQucdY+vK U3FYeL0lqPiQSqS7NsO1VxoexfpFJvYHXtPjNWnpOdb9Bx4UnQ2PnbN8v3yoKyZvZkgtrPhx dP1Q5M/u2KSAOG/Tpiif775eRm2vsqBz5EbR++jorIipifmugeZ99nt7DlZzXsoTZQbf7Tsi Mie9/U8v5w/5ObbkVwlGZJQmXh4WTKo18t8f6cUU9QIAAA== X-CFilter-Loop: Reflected On Mon, May 18, 2026 at 05:31:24PM -0700, Andrew Morton wrote: > The patch titled > Subject: Revert "mm: introduce a new page type for page pool in page type" > has been added to the -mm mm-hotfixes-unstable branch. Its filename is > revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type.patch > > This patch will shortly appear at > https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type.patch > > This patch will later appear in the mm-hotfixes-unstable branch at > git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** > > The -mm tree is included into linux-next via various > branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > and is updated there most days > > ------------------------------------------------------ > From: Byungchul Park > Subject: Revert "mm: introduce a new page type for page pool in page type" > Date: Fri, 15 May 2026 12:47:01 +0900 > > This reverts commit db359fccf212 ("mm: introduce a new page type for page > pool in page type") and a part of 735a309b4bfb9e ("net: add net_iov_init() > and use it > to initialize ->page_type"). ^ Check this out, Andrew. Byungchul > Netpp page_type'ed pages might be used in mapping so as to use @_mapcount. > However, since @page_type and @_mapcount are union'ed in struct page, > these two can't be used at the same time. Revert the commit introducing > page_type for Netpp for now. > > The patch will be retried once @page_type and @_mapcount get allowed to be > used at the same time. > > The revert also includes removal of @page_type initialization part > introduced by commit 735a309b4bfb9e ("net: add net_iov_init() and use it > to initialize ->page_type"), which will be restored on the retry. > > Link: https://lore.kernel.org/20260515034701.17027-1-byungchul@sk.com > Fixes: db359fccf212 ("mm: introduce a new page type for page pool in page type") > Signed-off-by: Byungchul Park > Reported-by: Dragos Tatulea > Closes: https://lore.kernel.org/all/982b9bc1-0a0a-4fc5-8e3a-3672db2b29a1@nvidia.com > Acked-by: Jakub Kicinski > Acked-by: David Hildenbrand (Arm) > Acked-by: Harry Yoo (Oracle) > Reviewed-by: Lorenzo Stoakes > Cc: Alexei Starovoitov > Cc: Baolin Wang > Cc: Brendan Jackman > Cc: David S. Miller > Cc: Eric Dumazet > Cc: Ilias Apalodimas > Cc: Jesper Dangaard Brouer > Cc: Johannes Weiner > Cc: John Fastabend > Cc: Leon Romanovsky > Cc: Liam R. Howlett > Cc: Mark Bloch > Cc: Matthew Wilcox (Oracle) > Cc: Michal Hocko > Cc: Mike Rapoport > Cc: Paolo Abeni > Cc: Pavel Begunkov > Cc: Saeed Mahameed > Cc: Simon Horman > Cc: Stanislav Fomichev > Cc: Suren Baghdasaryan > Cc: Tariq Toukan > Cc: Toke Hoiland-Jorgensen > Cc: Vlastimil Babka > Cc: Zi Yan > Signed-off-by: Andrew Morton > --- > > drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 2 > include/linux/mm.h | 27 +++++++++++-- > include/linux/page-flags.h | 6 -- > include/net/netmem.h | 19 --------- > mm/page_alloc.c | 13 +----- > net/core/netmem_priv.h | 23 ++++++----- > net/core/page_pool.c | 24 ----------- > 7 files changed, 46 insertions(+), 68 deletions(-) > > --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c > @@ -708,7 +708,7 @@ static void mlx5e_free_xdpsq_desc(struct > xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo); > page = xdpi.page.page; > > - /* No need to check PageNetpp() as we > + /* No need to check page_pool_page_is_pp() as we > * know this is a page_pool page. > */ > page_pool_recycle_direct(pp_page_to_nmdesc(page)->pp, > --- a/include/linux/mm.h~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/include/linux/mm.h > @@ -5174,9 +5174,10 @@ int arch_lock_shadow_stack_status(struct > * DMA mapping IDs for page_pool > * > * When DMA-mapping a page, page_pool allocates an ID (from an xarray) and > - * stashes it in the upper bits of page->pp_magic. Non-PP pages can have > - * arbitrary kernel pointers stored in the same field as pp_magic (since > - * it overlaps with page->lru.next), so we must ensure that we cannot > + * stashes it in the upper bits of page->pp_magic. We always want to be able to > + * unambiguously identify page pool pages (using page_pool_page_is_pp()). Non-PP > + * pages can have arbitrary kernel pointers stored in the same field as pp_magic > + * (since it overlaps with page->lru.next), so we must ensure that we cannot > * mistake a valid kernel pointer with any of the values we write into this > * field. > * > @@ -5211,6 +5212,26 @@ int arch_lock_shadow_stack_status(struct > #define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \ > PP_DMA_INDEX_SHIFT) > > +/* Mask used for checking in page_pool_page_is_pp() below. page->pp_magic is > + * OR'ed with PP_SIGNATURE after the allocation in order to preserve bit 0 for > + * the head page of compound page and bit 1 for pfmemalloc page, as well as the > + * bits used for the DMA index. page_is_pfmemalloc() is checked in > + * __page_pool_put_page() to avoid recycling the pfmemalloc page. > + */ > +#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL) > + > +#ifdef CONFIG_PAGE_POOL > +static inline bool page_pool_page_is_pp(const struct page *page) > +{ > + return (page->pp_magic & PP_MAGIC_MASK) == PP_SIGNATURE; > +} > +#else > +static inline bool page_pool_page_is_pp(const struct page *page) > +{ > + return false; > +} > +#endif > + > #define PAGE_SNAPSHOT_FAITHFUL (1 << 0) > #define PAGE_SNAPSHOT_PG_BUDDY (1 << 1) > #define PAGE_SNAPSHOT_PG_IDLE (1 << 2) > --- a/include/linux/page-flags.h~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/include/linux/page-flags.h > @@ -923,7 +923,6 @@ enum pagetype { > PGTY_zsmalloc = 0xf6, > PGTY_unaccepted = 0xf7, > PGTY_large_kmalloc = 0xf8, > - PGTY_netpp = 0xf9, > > PGTY_mapcount_underflow = 0xff > }; > @@ -1056,11 +1055,6 @@ PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmall > PAGE_TYPE_OPS(Unaccepted, unaccepted, unaccepted) > PAGE_TYPE_OPS(LargeKmalloc, large_kmalloc, large_kmalloc) > > -/* > - * Marks page_pool allocated pages. > - */ > -PAGE_TYPE_OPS(Netpp, netpp, netpp) > - > /** > * PageHuge - Determine if the page belongs to hugetlbfs > * @page: The page to test. > --- a/include/net/netmem.h~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/include/net/netmem.h > @@ -94,20 +94,10 @@ enum net_iov_type { > */ > struct net_iov { > struct netmem_desc desc; > - unsigned int page_type; > enum net_iov_type type; > struct net_iov_area *owner; > }; > > -/* Make sure 'the offset of page_type in struct page == the offset of > - * type in struct net_iov'. > - */ > -#define NET_IOV_ASSERT_OFFSET(pg, iov) \ > - static_assert(offsetof(struct page, pg) == \ > - offsetof(struct net_iov, iov)) > -NET_IOV_ASSERT_OFFSET(page_type, page_type); > -#undef NET_IOV_ASSERT_OFFSET > - > struct net_iov_area { > /* Array of net_iovs for this area. */ > struct net_iov *niovs; > @@ -127,11 +117,7 @@ static inline unsigned int net_iov_idx(c > return niov - net_iov_owner(niov)->niovs; > } > > -/* Initialize a niov: stamp the owning area, the memory provider type, > - * and the page_type "no type" sentinel expected by the page-type API > - * (see PAGE_TYPE_OPS in ) so that > - * page_pool_set_pp_info() can later call __SetPageNetpp() on a niov > - * cast to struct page. > +/* Initialize a niov: stamp the owning area, the memory provider type. > */ > static inline void net_iov_init(struct net_iov *niov, > struct net_iov_area *owner, > @@ -139,7 +125,6 @@ static inline void net_iov_init(struct n > { > niov->owner = owner; > niov->type = type; > - niov->page_type = UINT_MAX; > } > > /* netmem */ > @@ -245,7 +230,7 @@ static inline unsigned long netmem_pfn_t > */ > #define pp_page_to_nmdesc(p) \ > ({ \ > - DEBUG_NET_WARN_ON_ONCE(!PageNetpp(p)); \ > + DEBUG_NET_WARN_ON_ONCE(!page_pool_page_is_pp(p)); \ > __pp_page_to_nmdesc(p); \ > }) > > --- a/mm/page_alloc.c~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/mm/page_alloc.c > @@ -1035,6 +1035,7 @@ static inline bool page_expected_state(s > #ifdef CONFIG_MEMCG > page->memcg_data | > #endif > + page_pool_page_is_pp(page) | > (page->flags.f & check_flags))) > return false; > > @@ -1061,6 +1062,8 @@ static const char *page_bad_reason(struc > if (unlikely(page->memcg_data)) > bad_reason = "page still charged to cgroup"; > #endif > + if (unlikely(page_pool_page_is_pp(page))) > + bad_reason = "page_pool leak"; > return bad_reason; > } > > @@ -1377,17 +1380,9 @@ __always_inline bool __free_pages_prepar > mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); > folio->mapping = NULL; > } > - if (unlikely(page_has_type(page))) { > - /* networking expects to clear its page type before releasing */ > - if (is_check_pages_enabled()) { > - if (unlikely(PageNetpp(page))) { > - bad_page(page, "page_pool leak"); > - return false; > - } > - } > + if (unlikely(page_has_type(page))) > /* Reset the page_type (which overlays _mapcount) */ > page->page_type = UINT_MAX; > - } > > if (is_check_pages_enabled()) { > if (free_page_is_bad(page)) > --- a/net/core/netmem_priv.h~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/net/core/netmem_priv.h > @@ -8,18 +8,21 @@ static inline unsigned long netmem_get_p > return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK; > } > > -static inline bool netmem_is_pp(netmem_ref netmem) > +static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_magic) > +{ > + netmem_to_nmdesc(netmem)->pp_magic |= pp_magic; > +} > + > +static inline void netmem_clear_pp_magic(netmem_ref netmem) > { > - struct page *page; > + WARN_ON_ONCE(netmem_to_nmdesc(netmem)->pp_magic & PP_DMA_INDEX_MASK); > > - /* XXX: Now that the offset of page_type is shared between > - * struct page and net_iov, just cast the netmem to struct page > - * unconditionally by clearing NET_IOV if any, no matter whether > - * it comes from struct net_iov or struct page. This should be > - * adjusted once the offset is no longer shared. > - */ > - page = (struct page *)((__force unsigned long)netmem & ~NET_IOV); > - return PageNetpp(page); > + netmem_to_nmdesc(netmem)->pp_magic = 0; > +} > + > +static inline bool netmem_is_pp(netmem_ref netmem) > +{ > + return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE; > } > > static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool) > --- a/net/core/page_pool.c~revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type > +++ a/net/core/page_pool.c > @@ -707,18 +707,8 @@ s32 page_pool_inflight(const struct page > > void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) > { > - struct page *page; > - > netmem_set_pp(netmem, pool); > - > - /* XXX: Now that the offset of page_type is shared between > - * struct page and net_iov, just cast the netmem to struct page > - * unconditionally by clearing NET_IOV if any, no matter whether > - * it comes from struct net_iov or struct page. This should be > - * adjusted once the offset is no longer shared. > - */ > - page = (struct page *)((__force unsigned long)netmem & ~NET_IOV); > - __SetPageNetpp(page); > + netmem_or_pp_magic(netmem, PP_SIGNATURE); > > /* Ensuring all pages have been split into one fragment initially: > * page_pool_set_pp_info() is only called once for every page when it > @@ -733,17 +723,7 @@ void page_pool_set_pp_info(struct page_p > > void page_pool_clear_pp_info(netmem_ref netmem) > { > - struct page *page; > - > - /* XXX: Now that the offset of page_type is shared between > - * struct page and net_iov, just cast the netmem to struct page > - * unconditionally by clearing NET_IOV if any, no matter whether > - * it comes from struct net_iov or struct page. This should be > - * adjusted once the offset is no longer shared. > - */ > - page = (struct page *)((__force unsigned long)netmem & ~NET_IOV); > - __ClearPageNetpp(page); > - > + netmem_clear_pp_magic(netmem); > netmem_set_pp(netmem, NULL); > } > > _ > > Patches currently in -mm which might be from byungchul@sk.com are > > revert-mm-introduce-a-new-page-type-for-page-pool-in-page-type.patch