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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-c45ff70000001609-6d-6a0c067895a3 Date: Tue, 19 May 2026 15:42:59 +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: <20260519064259.GA57974@system.software.com> References: <20260519003125.5006AC2BCB7@smtp.kernel.org> <20260519051002.GA16061@system.software.com> 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: <20260519051002.GA16061@system.software.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA02Se0hTcRTH+d17vbubW9yW0a8HEQsJLO0lcXqvArkUkj0oyiBH3nI2p21l rjI0hV5q1pJ0aZhlqZXWfI9mNc2mgZmgLWdJ62GmpVNbqWG5ReR/H77ny/d8DxyGlI5QMxil +jCvUStUMlpEib6K8/zjaHHkoobyFZBdcpeG7KIKBEPDdgH8NtcjyH6RTEFX+QiCalMXgo/1 DgHcMQbDq/ZCBA9PV5LguGClITV5lATz8DcBnKoqIKC5Is0LLo/kk1DcaKGh930Q9GfUkdCZ Joeei81e4Hrei6CupJIAV0oODa1ZJgL0Lbk0vE/uRNBS66DgTHcnBaM/s2m4+vStQD6Hq+3t I7mywtcEZ6tpJLhqwxsBl2s8wpUW+HHGorM019H2kOasmaMUV/1uOZea9I3m+mpaaa6krJXi Bo2zQybtFq0K51XKWF6zcE2YKOKxq5aOMZyM6yg20Qno2p5ziGEwG4gznTvOIaEHnSM/kJsp 1hdXutopN9PsPGyzDZNu9mH9cVGXaZxFDMlmeeHPxeke0xT2BK5uyPewhAWcUOj0sJQ9gO1t n4i/+mTckPXBo5OsH7aNdRPuDiQ7E98eY9yykF2Ou3sueCxT2bn4ccUzwr0LsxkMfnWlBv0t Oh0/KbBR6Yg1TIg1TIg1/I/NRWQRkirVsVEKpSowIEKnVsYF7IuOMqLxj7gV/yu0Cg00b7Mg lkEysUT+WxQp9VLEanVRFoQZUuYjGSsRRkol4QrdMV4TvVdzRMVrLWgmQ8mmSZa4joaPX6g4 zB/k+Rhe829KMMIZCWhd3qXv1ndi+UaTebCY9l67cXPOx4wT9pCqpSlNln1DvU6pY5Z4b0qQ PWy+N282Ju5aef/8lyRRq3nX6XuhvwTxA003c8gts5ct6Ntf8bZHrzzUv9Ue7KvWb/qiy++/ 4a0vXb/zwYbE7S+v7+DFxw/ef7TU6pNu6HsT5qyxr0407hfLKG2EYrEfqdEq/gAeJrvzDQMA AA== X-Brightmail-Tracker: H4sIAAAAAAAAA02Ra0hTcRjG+Z9zdnY2XJ7M8p9G0boIRlZQ8IpWfikPgeW3qIwaecipm7J5 x8pU0qKmloGuVVJZbobGNC/DjdCyVCqZWWaZtfKWw0styxmzbRH57cfvfZ4PDy9D+tmoQEau TOVVSlmSlBZT4v3h+ZszaZ+ErUWmjaCru0+DztCIwDH3TggL5g4EupcFFIw+dCJoMY0iGO6w CaHGGA1vBvQIWgubSLAVP6PhUsE8Cea5SSHkNVcT0H69UwA9jRoBlDmrSKjtaqPB/nkvTF99 TMKQJhImSnsEMNttR/C4romA2YvXaeirMBFwxVpJw+eCIQTWdhsFReNDFMz/0tFw7ckHYeRa rt0+RXIN+rcE12/pIrgW7aCQqzSmcfXVIZzRcJ7m3r9upbln5fMU1/IpjLuUP0lzU5Y+mrs9 Nk1wdQ19FPfduDrG97A4Io5Pkqfzqi27jovjH8220yna05nva010LroRewGJGMxuxzPOn8jD FLsBN80OUB6m2WDc3z9Hetif3YwNoyY3ixmSrRDgsdoSb2gZm4NbOqu8LGEB5+pnvOzHnsTv Xo8Qf/1S3FnxxetJNgT3u8bdnnFzEL7nYjxaxIbh8Ylib2Q5uw4/anxKlCCJdlFbu6it/d+u RKQB+cuV6QqZPGlHqDoxPkspzww9kawwIvfn7576XdqMHL1RbYhlkNRHErkgTvATyNLVWYo2 hBlS6i9x1YkS/CRxsqxsXpV8TJWWxKvbUBBDSQMk+w7yx91TZKl8Is+n8Kp/V4IRBeainCjd CvHO+aiYFysL8x6czHaVKu6YtUetmm32OOycOvA1dc/YqcE3ZzQjIxllS2zHDgXzXeruBL2v pXz9YMQROZhjLEEa5eUi3e67jqlbGSscaWdrwnujf6za9Oo5fBP4HM4ujcc3hq0fz6WYc1w+ UTFsT6wlK3bNpnpZwM3hBimljpdtCyFVatkfdU6syPUCAAA= X-CFilter-Loop: Reflected On Tue, May 19, 2026 at 02:10:02PM +0900, Byungchul Park wrote: > 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. Hm.. I might have expressed that incorrectly in English. I just wanted you to check the '>' wrongly added :) Byungchul > > 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