From: Mike Rapoport <rppt@linux.ibm.com> To: Souptick Joarder <jrdr.linux@gmail.com> Cc: Michal Hocko <mhocko@suse.com>, Heiko Stuebner <heiko@sntech.de>, Peter Zijlstra <peterz@infradead.org>, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Linux-MM <linux-mm@kvack.org>, linux1394-devel@lists.sourceforge.net, Marek Szyprowski <m.szyprowski@samsung.com>, Stephen Rothwell <sfr@canb.auug.org.au>, oleksandr_andrushchenko@epam.com, joro@8bytes.org, Russell King - ARM Linux <linux@armlinux.org.uk>, Matthew Wilcox <willy@infradead.org>, airlied@linux.ie, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, treding@nvidia.com, linux-media@vger.kernel.org, Kees Cook <keescook@chromium.org>, pawel@osciak.com, Rik van Riel <riel@surriel.com>, iommu@lists.linux-foundation.org, rppt@linux.vnet.ibm.com, Boris Ostrovsky <boris.ostrovsky@oracle.com>, mchehab@kernel.org, iamjoonsoo.kim@lge.com, vbabka@suse.cz, Juergen Gross <jgross@suse.com>, hjc@rock-chips.com, xen-devel@lists.xen.org, Kyungmin Park <kyungmin.park@samsung.com>, stefanr@s5r6.in-berlin.de, Andrew Morton <akpm@linux-foundation.org>, robin.murphy@arm.com, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Subject: Re: [PATCHv2 1/9] mm: Introduce new vm_insert_range and vm_insert_range_buggy API Date: Thu, 31 Jan 2019 13:06:39 +0200 Message-ID: <20190131110638.GK28876@rapoport-lnx> (raw) In-Reply-To: <CAFqt6zbG089qCYBoZ8HCHPaRm+Yi=gHNboxy9y_qw9eVpSFjag@mail.gmail.com> On Thu, Jan 31, 2019 at 03:43:39PM +0530, Souptick Joarder wrote: > On Thu, Jan 31, 2019 at 2:09 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > On Thu, Jan 31, 2019 at 08:38:12AM +0530, Souptick Joarder wrote: > > > Previouly drivers have their own way of mapping range of > > > kernel pages/memory into user vma and this was done by > > > invoking vm_insert_page() within a loop. > > > > > > As this pattern is common across different drivers, it can > > > be generalized by creating new functions and use it across > > > the drivers. > > > > > > vm_insert_range() is the API which could be used to mapped > > > kernel memory/pages in drivers which has considered vm_pgoff > > > > > > vm_insert_range_buggy() is the API which could be used to map > > > range of kernel memory/pages in drivers which has not considered > > > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > > > > > > We _could_ then at a later "fix" these drivers which are using > > > vm_insert_range_buggy() to behave according to the normal vm_pgoff > > > offsetting simply by removing the _buggy suffix on the function > > > name and if that causes regressions, it gives us an easy way to revert. > > > > > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > > > Suggested-by: Russell King <linux@armlinux.org.uk> > > > Suggested-by: Matthew Wilcox <willy@infradead.org> > > > --- > > > include/linux/mm.h | 4 +++ > > > mm/memory.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > mm/nommu.c | 14 ++++++++++ > > > 3 files changed, 99 insertions(+) > > > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > > index 80bb640..25752b0 100644 > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -2565,6 +2565,10 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, > > > int remap_pfn_range(struct vm_area_struct *, unsigned long addr, > > > unsigned long pfn, unsigned long size, pgprot_t); > > > int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num); > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num); > > > vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, > > > unsigned long pfn); > > > vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, > > > diff --git a/mm/memory.c b/mm/memory.c > > > index e11ca9d..0a4bf57 100644 > > > --- a/mm/memory.c > > > +++ b/mm/memory.c > > > @@ -1520,6 +1520,87 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > > > } > > > EXPORT_SYMBOL(vm_insert_page); > > > > > > +/** > > > + * __vm_insert_range - insert range of kernel pages into user vma > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * @offset: user's requested vm_pgoff > > > + * > > > + * This allows drivers to insert range of kernel pages they've allocated > > > + * into a user vma. > > > + * > > > + * If we fail to insert any page into the vma, the function will return > > > + * immediately leaving any previously inserted pages present. Callers > > > + * from the mmap handler may immediately return the error as their caller > > > + * will destroy the vma, removing any successfully inserted pages. Other > > > + * callers should make their own arrangements for calling unmap_region(). > > > + * > > > + * Context: Process context. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +static int __vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num, unsigned long offset) > > > +{ > > > + unsigned long count = vma_pages(vma); > > > + unsigned long uaddr = vma->vm_start; > > > + int ret, i; > > > + > > > + /* Fail if the user requested offset is beyond the end of the object */ > > > + if (offset > num) > > > + return -ENXIO; > > > + > > > + /* Fail if the user requested size exceeds available object size */ > > > + if (count > num - offset) > > > + return -ENXIO; > > > + > > > + for (i = 0; i < count; i++) { > > > + ret = vm_insert_page(vma, uaddr, pages[offset + i]); > > > + if (ret < 0) > > > + return ret; > > > + uaddr += PAGE_SIZE; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > +/** > > > + * vm_insert_range - insert range of kernel pages starts with non zero offset > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * > > > + * Maps an object consisting of `num' `pages', catering for the user's > > > + * requested vm_pgoff > > > + * > > > > The elaborate description you've added to __vm_insert_range() is better put > > here, as this is the "public" function. > > Ok, will add it in v3. Which means __vm_insert_range() still needs a short > description ? It won't hurt ;-) > > > > > + * Context: Process context. Called by mmap handlers. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return __vm_insert_range(vma, pages, num, vma->vm_pgoff); > > > +} > > > +EXPORT_SYMBOL(vm_insert_range); > > > + > > > +/** > > > + * vm_insert_range_buggy - insert range of kernel pages starts with zero offset > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * > > > + * Maps a set of pages, always starting at page[0] > > > > Here I'd add something like: > > > > Similar to vm_insert_range(), except that it explicitly sets @vm_pgoff to > > 0. This function is intended for the drivers that did not consider > > @vm_pgoff. > > Ok. > > > > > > vm_insert_range_buggy() is the API which could be used to map > > > range of kernel memory/pages in drivers which has not considered > > > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > > > > > + * > > > + * Context: Process context. Called by mmap handlers. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return __vm_insert_range(vma, pages, num, 0); > > > +} > > > +EXPORT_SYMBOL(vm_insert_range_buggy); > > > + > > > static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, > > > pfn_t pfn, pgprot_t prot, bool mkwrite) > > > { > > > diff --git a/mm/nommu.c b/mm/nommu.c > > > index 749276b..21d101e 100644 > > > --- a/mm/nommu.c > > > +++ b/mm/nommu.c > > > @@ -473,6 +473,20 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > > > } > > > EXPORT_SYMBOL(vm_insert_page); > > > > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return -EINVAL; > > > +} > > > +EXPORT_SYMBOL(vm_insert_range); > > > + > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return -EINVAL; > > > +} > > > +EXPORT_SYMBOL(vm_insert_range_buggy); > > > + > > > /* > > > * sys_brk() for the most part doesn't need the global kernel > > > * lock, except when an application is doing something nasty > > > -- > > > 1.9.1 > > > > > > > -- > > Sincerely yours, > > Mike. > > > -- Sincerely yours, Mike. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-01-31 3:08 Souptick Joarder 2019-01-31 8:38 ` Mike Rapoport 2019-01-31 10:13 ` Souptick Joarder 2019-01-31 11:06 ` Mike Rapoport [this message] 2019-02-07 15:49 ` Souptick Joarder 2019-02-07 15:57 ` Mike Rapoport 2019-02-07 16:07 ` Souptick Joarder 2019-02-07 16:04 ` Mike Rapoport 2019-02-07 16:47 ` Matthew Wilcox 2019-02-08 5:22 ` Souptick Joarder 2019-02-11 17:06 ` Souptick Joarder 2019-01-31 12:06 ` Heiko Stuebner 2019-01-31 12:31 ` Souptick Joarder 2019-01-31 12:34 ` Heiko Stuebner 2019-02-01 12:38 ` Souptick Joarder
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20190131110638.GK28876@rapoport-lnx \ --to=rppt@linux.ibm.com \ --cc=airlied@linux.ie \ --cc=akpm@linux-foundation.org \ --cc=boris.ostrovsky@oracle.com \ --cc=dri-devel@lists.freedesktop.org \ --cc=heiko@sntech.de \ --cc=hjc@rock-chips.com \ --cc=iamjoonsoo.kim@lge.com \ --cc=iommu@lists.linux-foundation.org \ --cc=jgross@suse.com \ --cc=joro@8bytes.org \ --cc=jrdr.linux@gmail.com \ --cc=keescook@chromium.org \ --cc=kirill.shutemov@linux.intel.com \ --cc=kyungmin.park@samsung.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-media@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=linux-rockchip@lists.infradead.org \ --cc=linux1394-devel@lists.sourceforge.net \ --cc=linux@armlinux.org.uk \ --cc=m.szyprowski@samsung.com \ --cc=mchehab@kernel.org \ --cc=mhocko@suse.com \ --cc=oleksandr_andrushchenko@epam.com \ --cc=pawel@osciak.com \ --cc=peterz@infradead.org \ --cc=riel@surriel.com \ --cc=robin.murphy@arm.com \ --cc=rppt@linux.vnet.ibm.com \ --cc=sfr@canb.auug.org.au \ --cc=stefanr@s5r6.in-berlin.de \ --cc=treding@nvidia.com \ --cc=vbabka@suse.cz \ --cc=willy@infradead.org \ --cc=xen-devel@lists.xen.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Linux-ARM-Kernel Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \ linux-arm-kernel@lists.infradead.org public-inbox-index linux-arm-kernel Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel AGPL code for this site: git clone https://public-inbox.org/public-inbox.git