kernel/linux.git/mm/process_vm_access.c, branch v6.19.11

mm: refactor mm_access() to not return NULL

2024-11-06T00:56:23+00:00

mm_access() can return NULL if the mm is not found, but this is handled the same as an error in all callers, with some translating this into an -ESRCH error. Only proc_mem_open() returns NULL if no mm is found, however in this case it is clearer and makes more sense to explicitly handle the error. Additionally we take the opportunity to refactor the function to eliminate unnecessary nesting. Simplify things by simply returning -ESRCH if no mm is found - this both eliminates confusing use of the IS_ERR_OR_NULL() macro, and simplifies callers which would return -ESRCH by returning this error directly. [lorenzo.stoakes@oracle.com: prefer neater pointer error comparison] Link: https://lkml.kernel.org/r/2fae1834-749a-45e1-8594-5e5979cf7103@lucifer.local Link: https://lkml.kernel.org/r/20240924201023.193135-1-lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Suggested-by: Arnd Bergmann Cc: Al Viro Signed-off-by: Andrew Morton

mm: fix process_vm_rw page counts

2023-12-11T00:51:39+00:00

1. There is a "-1" missing in the page number calculation in process_vm_rw_core. While this can't break anything, it can cause unnecessary allocations in certain cases: Consider handling an iovec ranging over PVM_MAX_PP_ARRAY_COUNT pages that is also aligned to a page boundary. While pp_stack could hold references to such an amount of pinned pages, nr_pages yields (PVM_MAX_PP_ARRAY + 1) in process_vm_rw_core. Consequently, a larger buffer is allocated with kmalloc for no reason. For any page boundary aligned iovec that is a multiple of PAGE_SIZE and larger than PVM_MAX_PP_ARRAY_COUNT pages, nr_pages will be too big by 1 and thus kmalloc allocates excess space for one more pointer. 2. max_pages_per_loop is constant and there is no reason to have it as a variable. A macro does the job just fine and saves memory. 3. Replaced "sizeof(struct pages *)" with "sizeof(struct page *)" to have matching types for allocation and prevent confusion. Link: https://lkml.kernel.org/r/20231111184859.44264-1-yjnworkstation@gmail.com Signed-off-by: York Jasper Niebuhr Signed-off-by: Andrew Morton

mm/gup: remove unused vmas parameter from pin_user_pages_remote()

2023-06-09T23:25:25+00:00

No invocation of pin_user_pages_remote() uses the vmas parameter, so remove it. This forms part of a larger patch set eliminating the use of the vmas parameters altogether. Link: https://lkml.kernel.org/r/28f000beb81e45bf538a2aaa77c90f5482b67a32.1684350871.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Acked-by: David Hildenbrand Reviewed-by: Jason Gunthorpe Reviewed-by: Christoph Hellwig Cc: Catalin Marinas Cc: Christian König Cc: Dennis Dalessandro Cc: Greg Kroah-Hartman Cc: Janosch Frank Cc: Jarkko Sakkinen Cc: Jens Axboe Cc: Matthew Wilcox (Oracle) Cc: Sakari Ailus Cc: Sean Christopherson Signed-off-by: Andrew Morton

use less confusing names for iov_iter direction initializers

2022-11-25T18:01:55+00:00

READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro

mm/process_vm_access.c: remove duplicate include

2021-05-05T18:27:27+00:00

'linux/compat.h' included in 'process_vm_access.c' is duplicated. Link: https://lkml.kernel.org/r/20210306132122.220431-1-zhang.yunkai@zte.com.cn Signed-off-by: Zhang Yunkai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/process_vm_access.c: include compat.h

2021-01-13T02:12:54+00:00

Fix the build error: mm/process_vm_access.c:277:5: error: implicit declaration of function 'in_compat_syscall'; did you mean 'in_ia32_syscall'? [-Werror=implicit-function-declaration] Fixes: 38dc5079da7081e "Fix compat regression in process_vm_rw()" Reported-by: syzbot+5b0d0de84d6c65b8dd2b@syzkaller.appspotmail.com Cc: Kyle Huey Cc: Jens Axboe Cc: Al Viro Cc: Christoph Hellwig Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/process_vm_access: remove redundant initialization of iov_r

2020-12-15T20:13:46+00:00

The pointer iov_r is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and can be removed. Link: https://lkml.kernel.org/r/20201102120614.694917-1-colin.king@canonical.com Signed-off-by: Colin Ian King Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/process_vm_access: Add missing #include

2020-10-27T19:41:29+00:00

With e.g. m68k/defconfig: mm/process_vm_access.c: In function ‘process_vm_rw’: mm/process_vm_access.c:277:5: error: implicit declaration of function ‘in_compat_syscall’ [-Werror=implicit-function-declaration] 277 | in_compat_syscall()); | ^~~~~~~~~~~~~~~~~ Fix this by adding #include . Reported-by: noreply@ellerman.id.au Reported-by: damian Reported-by: Naresh Kamboju Fixes: 38dc5079da7081e8 ("Fix compat regression in process_vm_rw()") Signed-off-by: Geert Uytterhoeven Acked-by: Jens Axboe Signed-off-by: Linus Torvalds

Fix compat regression in process_vm_rw()

2020-10-27T16:57:46+00:00

The removal of compat_process_vm_{readv,writev} didn't change process_vm_rw(), which always assumes it's not doing a compat syscall. Instead of passing in 'false' unconditionally for 'compat', make it conditional on in_compat_syscall(). [ Both Al and Christoph point out that trying to access a 64-bit process from a 32-bit one cannot work anyway, and is likely better prohibited, but that's a separate issue - Linus ] Fixes: c3973b401ef2 ("mm: remove compat_process_vm_{readv,writev}") Reported-and-tested-by: Kyle Huey Signed-off-by: Jens Axboe Acked-by: Al Viro Reviewed-by: Christoph Hellwig Signed-off-by: Linus Torvalds

mm: remove compat_process_vm_{readv,writev}

2020-10-03T04:02:15+00:00

Now that import_iovec handles compat iovecs, the native syscalls can be used for the compat case as well. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro