lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <56696a72-24fa-958e-e6a1-7a17c9e54081@redhat.com> Date: Tue, 2 May 2023 18:38:53 +0200 From: David Hildenbrand <david@...hat.com> To: Lorenzo Stoakes <lstoakes@...il.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org> Cc: Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>, Matthew Wilcox <willy@...radead.org>, Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>, Leon Romanovsky <leon@...nel.org>, Christian Benvenuti <benve@...co.com>, Nelson Escobar <neescoba@...co.com>, Bernard Metzler <bmt@...ich.ibm.com>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Mark Rutland <mark.rutland@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Bjorn Topel <bjorn@...nel.org>, Magnus Karlsson <magnus.karlsson@...el.com>, Maciej Fijalkowski <maciej.fijalkowski@...el.com>, Jonathan Lemon <jonathan.lemon@...il.com>, "David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Christian Brauner <brauner@...nel.org>, Richard Cochran <richardcochran@...il.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Jesper Dangaard Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, linux-fsdevel@...r.kernel.org, linux-perf-users@...r.kernel.org, netdev@...r.kernel.org, bpf@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>, Jason Gunthorpe <jgg@...dia.com>, John Hubbard <jhubbard@...dia.com>, Jan Kara <jack@...e.cz>, "Kirill A . Shutemov" <kirill@...temov.name>, Pavel Begunkov <asml.silence@...il.com>, Mika Penttila <mpenttil@...hat.com>, Dave Chinner <david@...morbit.com>, Theodore Ts'o <tytso@....edu>, Peter Xu <peterx@...hat.com>, Matthew Rosato <mjrosato@...ux.ibm.com>, "Paul E . McKenney" <paulmck@...nel.org>, Christian Borntraeger <borntraeger@...ux.ibm.com> Subject: Re: [PATCH v7 1/3] mm/mmap: separate writenotify and dirty tracking logic On 02.05.23 18:34, Lorenzo Stoakes wrote: > vma_wants_writenotify() is specifically intended for setting PTE page table > flags, accounting for existing PTE flag state and whether that might > already be read-only while mixing this check with a check whether the > filesystem performs dirty tracking. > > Separate out the notions of dirty tracking and a PTE write notify checking > in order that we can invoke the dirty tracking check from elsewhere. > > Note that this change introduces a very small duplicate check of the > separated out vm_ops_needs_writenotify(). This is necessary to avoid making > vma_needs_dirty_tracking() needlessly complicated (e.g. passing a > check_writenotify flag or having it assume this check was already > performed). This is such a small check that it doesn't seem too egregious > to do this. > > Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com> > Reviewed-by: John Hubbard <jhubbard@...dia.com> > Reviewed-by: Mika Penttilä <mpenttil@...hat.com> > Reviewed-by: Jan Kara <jack@...e.cz> > Reviewed-by: Jason Gunthorpe <jgg@...dia.com> > --- > include/linux/mm.h | 1 + > mm/mmap.c | 36 +++++++++++++++++++++++++++--------- > 2 files changed, 28 insertions(+), 9 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 27ce77080c79..7b1d4e7393ef 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2422,6 +2422,7 @@ extern unsigned long move_page_tables(struct vm_area_struct *vma, > #define MM_CP_UFFD_WP_ALL (MM_CP_UFFD_WP | \ > MM_CP_UFFD_WP_RESOLVE) > > +bool vma_needs_dirty_tracking(struct vm_area_struct *vma); > int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot); > static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma) > { > diff --git a/mm/mmap.c b/mm/mmap.c > index 5522130ae606..295c5f2e9bd9 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1475,6 +1475,31 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) > } > #endif /* __ARCH_WANT_SYS_OLD_MMAP */ > > +/* Do VMA operations imply write notify is required? */ > +static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops) > +{ > + return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite); > +} > + > +/* > + * Does this VMA require the underlying folios to have their dirty state > + * tracked? > + */ > +bool vma_needs_dirty_tracking(struct vm_area_struct *vma) > +{ Sorry for not noticing this earlier, but ... what about MAP_PRIVATE mappings? When we write, we populate an anon page, which will work as expected ... because we don't have to notify the fs? I think you really also want the "If it was private or non-writable, the write bit is already clear */" part as well and remove "false" in that case. Or was there a good reason to disallow private mappings as well? -- Thanks, David / dhildenb
Powered by blists - more mailing lists