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Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Alexander Shishkin , Maxime Coquelin , Alexandre Torgue , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Bodo Stroesser , "Martin K . Petersen" , David Howells , Marc Dionne , Alexander Viro , Christian Brauner , Jan Kara , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-mtd@lists.infradead.org, linux-staging@lists.linux.dev, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Ryan Roberts Subject: Re: [PATCH v3 15/16] mm: add mmap_action_map_kernel_pages[_full]() Message-ID: <20260320210812.GA3988975@ax162> References: <54ff3670662e10a66ce0c1a13c0ae93b99a5f201.1773944114.git.ljs@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54ff3670662e10a66ce0c1a13c0ae93b99a5f201.1773944114.git.ljs@kernel.org> X-Stat-Signature: oqoxx5y8jso3cgpi641ud137d5djo3gg X-Rspam-User: X-Rspamd-Queue-Id: 5A4B340011 X-Rspamd-Server: rspam12 X-HE-Tag: 1774040904-953320 X-HE-Meta: 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 L3xXNeHE 3DjWzAxO7M2G1BI1giRKijrTe78NXR32e1iyaQm/74lYdZM12IhEZR/z/pSJ8nCuXZCIaRWolz4g5/gpoYStw4Y6+HDuT1Fz/p+CHU91nu7AU0BaYug+5Ycc+Qy1uMQ6AoOJ2rr1JPJQiDts7fBTtX5RZHDIcFG//GLYqi81T3gxO4LDVhqYvA6VQQKWOIBbQreeX03dYCgXgEqU2DcJb9ynJDH85Ucu9e0L2u+J0/0wiwwYqTMnij3ocYo/nP8xIxxUCNhV3n+JwNTSdvFiOu1chwzZ433Fbwm0F6XNxhMvEWOLwEFFsKiYyc9GwBeyQHZc6IIeFnUidungCnANnLQSaS+8ZOiLgxPPIQ9zqvHuZ7Dx6gYGFB0Sj2m77mPqODz3r2cvJ8PppC1QoEriPavT22MAE+bvbhVK4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Lorenzo, On Thu, Mar 19, 2026 at 06:23:39PM +0000, Lorenzo Stoakes (Oracle) wrote: > A user can invoke mmap_action_map_kernel_pages() to specify that the > mapping should map kernel pages starting from desc->start of a specified > number of pages specified in an array. > > In order to implement this, adjust mmap_action_prepare() to be able to > return an error code, as it makes sense to assert that the specified > parameters are valid as quickly as possible as well as updating the VMA > flags to include VMA_MIXEDMAP_BIT as necessary. > > This provides an mmap_prepare equivalent of vm_insert_pages(). We > additionally update the existing vm_insert_pages() code to use > range_in_vma() and add a new range_in_vma_desc() helper function for the > mmap_prepare case, sharing the code between the two in range_is_subset(). > > We add both mmap_action_map_kernel_pages() and > mmap_action_map_kernel_pages_full() to allow for both partial and full VMA > mappings. > > We update the documentation to reflect the new features. > > Finally, we update the VMA tests accordingly to reflect the changes. > > Reviewed-by: Suren Baghdasaryan > Signed-off-by: Lorenzo Stoakes (Oracle) ... > diff --git a/mm/util.c b/mm/util.c > index 8cf59267a9ac..682d0d24e1c6 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -1446,6 +1446,8 @@ int mmap_action_prepare(struct vm_area_desc *desc) > return io_remap_pfn_range_prepare(desc); > case MMAP_SIMPLE_IO_REMAP: > return simple_ioremap_prepare(desc); > + case MMAP_MAP_KERNEL_PAGES: > + return map_kernel_pages_prepare(desc); > } > > WARN_ON_ONCE(1); > @@ -1476,6 +1478,9 @@ int mmap_action_complete(struct vm_area_struct *vma, > case MMAP_REMAP_PFN: > err = remap_pfn_range_complete(vma, action); > break; > + case MMAP_MAP_KERNEL_PAGES: > + err = map_kernel_pages_complete(vma, action); > + break; > case MMAP_IO_REMAP_PFN: > case MMAP_SIMPLE_IO_REMAP: > /* Should have been delegated. */ > @@ -1497,6 +1502,7 @@ int mmap_action_prepare(struct vm_area_desc *desc) > case MMAP_REMAP_PFN: > case MMAP_IO_REMAP_PFN: > case MMAP_SIMPLE_IO_REMAP: > + case MMAP_MAP_KERNEL_PAGES: > WARN_ON_ONCE(1); /* nommu cannot handle these. */ > break; > } Not sure if it has been reported/addressed yet but it looks like mmap_action_complete() was missed here, as pointed out by clang: $ make -skj"$(nproc)" ARCH=arm LLVM=1 mrproper allnoconfig mm/util.o mm/util.c:1520:10: warning: enumeration value 'MMAP_MAP_KERNEL_PAGES' not handled in switch [-Wswitch] 1520 | switch (action->type) { | ^~~~~~~~~~~~ I assume diff --git a/mm/util.c b/mm/util.c index 682d0d24e1c6..c41c119a5a74 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1523,6 +1523,7 @@ int mmap_action_complete(struct vm_area_struct *vma, case MMAP_REMAP_PFN: case MMAP_IO_REMAP_PFN: case MMAP_SIMPLE_IO_REMAP: + case MMAP_MAP_KERNEL_PAGES: WARN_ON_ONCE(1); /* nommu cannot handle this. */ err = -EINVAL; -- should be the fix? Cheers, Nathan