kernel/linux.git/lib/scatterlist.c, branch v6.12.80

mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios

2024-09-12T10:20:21+00:00

Define a data structure, struct folio_queue, to represent a sequence of folios and a kernel-internal I/O iterator type, ITER_FOLIOQ, to allow a list of folio_queue structures to be used to provide a buffer to iov_iter-taking functions, such as sendmsg and recvmsg. The folio_queue structure looks like: struct folio_queue { struct folio_batch vec; u8 orders[PAGEVEC_SIZE]; struct folio_queue *next; struct folio_queue *prev; unsigned long marks; unsigned long marks2; }; It does not use a list_head so that next and/or prev can be set to NULL at the ends of the list, allowing iov_iter-handling routines to determine that they *are* the ends without needing to store a head pointer in the iov_iter struct. A folio_batch struct is used to hold the folio pointers which allows the batch to be passed to batch handling functions. Two mark bits are available per slot. The intention is to use at least one of them to mark folios that need putting, but that might not be ultimately necessary. Accessor functions are used to access the slots to do the masking and an additional accessor function is used to indicate the size of the array. The order of each folio is also stored in the structure to avoid the need for iov_iter_advance() and iov_iter_revert() to have to query each folio to find its size. With careful barriering, this can be used as an extending buffer with new folios inserted and new folio_queue structs added without the need for a lock. Further, provided we always keep at least one struct in the buffer, we can also remove consumed folios and consumed structs from the head end as we without the need for locks. [Questions/thoughts] (1) To manage this, I need a head pointer, a tail pointer, a tail slot number (assuming insertion happens at the tail end and the next pointers point from head to tail). Should I put these into a struct of their own, say "folio_queue_head" or "rolling_buffer"? I will end up with two of these in netfs_io_request eventually, one keeping track of the pagecache I'm dealing with for buffered I/O and the other to hold a bounce buffer when we need one. (2) Should I make the slots {folio,off,len} or bio_vec? (3) This is intended to replace ITER_XARRAY eventually. Using an xarray in I/O iteration requires the taking of the RCU read lock, doing copying under the RCU read lock, walking the xarray (which may change under us), handling retries and dealing with special values. The advantage of ITER_XARRAY is that when we're dealing with the pagecache directly, we don't need any allocation - but if we're doing encrypted comms, there's a good chance we'd be using a bounce buffer anyway. This will require afs, erofs, cifs, orangefs and fscache to be converted to not use this. afs still uses it for dirs and symlinks; some of erofs usages should be easy to change, but there's one which won't be so easy; ceph's use via fscache can be fixed by porting ceph to netfslib; cifs is using xarray as a bounce buffer - that can be moved to use sheaves instead; and orangefs has a similar problem to erofs - maybe orangefs could use netfslib? Signed-off-by: David Howells cc: Matthew Wilcox cc: Jeff Layton cc: Steve French cc: Ilya Dryomov cc: Gao Xiang cc: Mike Marshall cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: ceph-devel@vger.kernel.org cc: linux-erofs@lists.ozlabs.org cc: devel@lists.orangefs.org Link: https://lore.kernel.org/r/20240814203850.2240469-13-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

Fix a potential infinite loop in extract_user_to_sg()

2024-04-26T19:35:57+00:00

Fix extract_user_to_sg() so that it will break out of the loop if iov_iter_extract_pages() returns 0 rather than looping around forever. [Note that I've included two fixes lines as the function got moved to a different file and renamed] Fixes: 85dd2c8ff368 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator") Fixes: f5f82cd18732 ("Move netfs_extract_iter_to_sg() to lib/scatterlist.c") Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: Herbert Xu cc: netfs@lists.linux.dev Link: https://lore.kernel.org/r/1967121.1714034372@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski

scatterlist: add missing function params to kernel-doc

2023-09-19T20:21:33+00:00

Describe missing function parameters to prevent kernel-doc warnings: lib/scatterlist.c:288: warning: Function parameter or member 'first_chunk' not described in '__sg_alloc_table' lib/scatterlist.c:800: warning: Function parameter or member 'flags' not described in 'sg_miter_start' Link: https://lkml.kernel.org/r/20230912060848.4673-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton

crypto, cifs: fix error handling in extract_iter_to_sg()

2023-08-04T20:03:40+00:00

Fix error handling in extract_iter_to_sg(). Pages need to be unpinned, not put in extract_user_to_sg() when handling IOVEC/UBUF sources. The bug may result in a warning like the following: WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:27 [inline] WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline] WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 raw_atomic_add include/linux/atomic/atomic-arch-fallback.h:537 [inline] WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 atomic_add include/linux/atomic/atomic-instrumented.h:105 [inline] WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 try_grab_page+0x108/0x160 mm/gup.c:252 ... pc : try_grab_page+0x108/0x160 mm/gup.c:229 lr : follow_page_pte+0x174/0x3e4 mm/gup.c:651 ... Call trace: __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:27 [inline] arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline] raw_atomic_add include/linux/atomic/atomic-arch-fallback.h:537 [inline] atomic_add include/linux/atomic/atomic-instrumented.h:105 [inline] try_grab_page+0x108/0x160 mm/gup.c:252 follow_pmd_mask mm/gup.c:734 [inline] follow_pud_mask mm/gup.c:765 [inline] follow_p4d_mask mm/gup.c:782 [inline] follow_page_mask+0x12c/0x2e4 mm/gup.c:839 __get_user_pages+0x174/0x30c mm/gup.c:1217 __get_user_pages_locked mm/gup.c:1448 [inline] __gup_longterm_locked+0x94/0x8f4 mm/gup.c:2142 internal_get_user_pages_fast+0x970/0xb60 mm/gup.c:3140 pin_user_pages_fast+0x4c/0x60 mm/gup.c:3246 iov_iter_extract_user_pages lib/iov_iter.c:1768 [inline] iov_iter_extract_pages+0xc8/0x54c lib/iov_iter.c:1831 extract_user_to_sg lib/scatterlist.c:1123 [inline] extract_iter_to_sg lib/scatterlist.c:1349 [inline] extract_iter_to_sg+0x26c/0x6fc lib/scatterlist.c:1339 hash_sendmsg+0xc0/0x43c crypto/algif_hash.c:117 sock_sendmsg_nosec net/socket.c:725 [inline] sock_sendmsg+0x54/0x60 net/socket.c:748 ____sys_sendmsg+0x270/0x2ac net/socket.c:2494 ___sys_sendmsg+0x80/0xdc net/socket.c:2548 __sys_sendmsg+0x68/0xc4 net/socket.c:2577 __do_sys_sendmsg net/socket.c:2586 [inline] __se_sys_sendmsg net/socket.c:2584 [inline] __arm64_sys_sendmsg+0x24/0x30 net/socket.c:2584 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x48/0x114 arch/arm64/kernel/syscall.c:52 el0_svc_common.constprop.0+0x44/0xe4 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x38/0xa4 arch/arm64/kernel/syscall.c:191 el0_svc+0x2c/0xb0 arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0xc0/0xc4 arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:591 Link: https://lkml.kernel.org/r/20571.1690369076@warthog.procyon.org.uk Fixes: 018584697533 ("netfs: Add a function to extract an iterator into a scatterlist") Reported-by: syzbot+9b82859567f2e50c123e@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-mm/000000000000273d0105ff97bf56@google.com/ Signed-off-by: David Howells Reviewed-by: David Hildenbrand Acked-by: Steve French Cc: Sven Schnelle Cc: Herbert Xu Cc: Jeff Layton Cc: Shyam Prasad N Cc: Rohith Surabattula Cc: Jens Axboe Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton

Merge tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2023-07-06T17:06:04+00:00

Pull asm-generic updates from Arnd Bergmann: "These are cleanups for architecture specific header files: - the comments in include/linux/syscalls.h have gone out of sync and are really pointless, so these get removed - The asm/bitsperlong.h header no longer needs to be architecture specific on modern compilers, so use a generic version for newer architectures that use new enough userspace compilers - A cleanup for virt_to_pfn/virt_to_bus to have proper type checking, forcing the use of pointers" * tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: syscalls: Remove file path comments from headers tools arch: Remove uapi bitsperlong.h of hexagon and microblaze asm-generic: Unify uapi bitsperlong.h for arm64, riscv and loongarch m68k/mm: Make pfn accessors static inlines arm64: memory: Make virt_to_pfn() a static inline ARM: mm: Make virt_to_pfn() a static inline asm-generic/page.h: Make pfn accessors static inlines xen/netback: Pass (void *) to virt_to_page() netfs: Pass a pointer to virt_to_page() cifs: Pass a pointer to virt_to_page() in cifsglob cifs: Pass a pointer to virt_to_page() riscv: mm: init: Pass a pointer to virt_to_page() ARC: init: Pass a pointer to virt_to_pfn() in init m68k: Pass a pointer to virt_to_pfn() virt_to_page() fs/proc/kcore.c: Pass a pointer to virt_addr_valid()

Move netfs_extract_iter_to_sg() to lib/scatterlist.c

2023-06-08T11:42:33+00:00

Move netfs_extract_iter_to_sg() to lib/scatterlist.c as it's going to be used by more than just network filesystems (AF_ALG, for example). Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Jens Axboe cc: Herbert Xu cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Matthew Wilcox cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni

lib/scatterlist: Fix to calculate the last_pg properly

2023-01-16T16:08:31+00:00

The last_pg is wrong, it is actually the first page of the last scatterlist element. To get the last page of the last scatterlist element we have to add prv->length. So it is checking mergability against the wrong page, Further, a SG element is not guaranteed to end on a page boundary, so we have to check the sub page location also for merge eligibility. Fix the above by checking physical contiguity based on PFNs, compute the actual last page and then call pages_are_mergable(). Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages") Link: https://lore.kernel.org/r/20230111101054.188136-1-yishaih@nvidia.com Reported-by: Jason Gunthorpe Signed-off-by: Yishai Hadas Reviewed-by: Chaitanya Kulkarni Signed-off-by: Jason Gunthorpe

lib/scatterlist: Fix to merge contiguous pages into the last SG properly

2023-01-05T20:01:05+00:00

When sg_alloc_append_table_from_pages() calls to pages_are_mergeable() in its 'sgt_append->prv' flow to check whether it can merge contiguous pages into the last SG, it passes the page arguments in the wrong order. The first parameter should be the next candidate page to be merged to the last page and not the opposite. The current code leads to a corrupted SG which resulted in OOPs and unexpected errors when non-contiguous pages are merged wrongly. Fix to pass the page parameters in the right order. Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages") Link: https://lore.kernel.org/r/20230105112339.107969-1-yishaih@nvidia.com Signed-off-by: Yishai Hadas Reviewed-by: Jason Gunthorpe Reviewed-by: Logan Gunthorpe Signed-off-by: Jason Gunthorpe

lib/scatterlist: add check when merging zone device pages

2022-11-09T18:29:21+00:00

Consecutive zone device pages should not be merged into the same sgl or bvec segment with other types of pages or if they belong to different pgmaps. Otherwise getting the pgmap of a given segment is not possible without scanning the entire segment. This helper returns true either if both pages are not zone device pages or both pages are zone device pages with the same pgmap. Factor out the check for page mergability into a pages_are_mergable() helper and add a check with zone_device_pages_are_mergeable(). Signed-off-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20221021174116.7200-6-logang@deltatee.com Signed-off-by: Jens Axboe

lib/scatterlist: use matched parameter type when calling __sg_free_table()

2022-07-18T00:31:39+00:00

commit 4635873c561a ("scsi: lib/sg_pool.c: improve APIs for allocating sg pool") changeed @(bool)skip_first_chunk of __sg_free_table() to @(unsigned int)nents_first_chunk, so use unsigend int type instead of bool type (false -> 0) when calling the function in sg_free_append_table() and sg_free_table(). Link: https://lkml.kernel.org/r/20220629030241.84559-1-wuchi.zero@gmail.com Signed-off-by: wuchi Reviewed-by: Ming Lei Cc: Maor Gottlieb Cc: Christoph Hellwig Signed-off-by: Andrew Morton