diff options
| author | David Hildenbrand <david@redhat.com> | 2025-09-01 17:03:43 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-09-21 14:22:06 -0700 |
| commit | 6972706f95926838f9bd3ec2b2393c034bdb85ba (patch) | |
| tree | bec182504813703d94bf09266730a14e9e2c9a46 /include/linux | |
| parent | b71ddc9ecc4d142465617d60e16a8a6ff154fdea (diff) | |
mm/cma: refuse handing out non-contiguous page ranges
Let's disallow handing out PFN ranges with non-contiguous pages, so we can
remove the nth-page usage in __cma_alloc(), and so any callers don't have
to worry about that either when wanting to blindly iterate pages.
This is really only a problem in configs with SPARSEMEM but without
SPARSEMEM_VMEMMAP, and only when we would cross memory sections in some
cases.
Will this cause harm? Probably not, because it's mostly 32bit that does
not support SPARSEMEM_VMEMMAP. If this ever becomes a problem we could
look into allocating the memmap for the memory sections spanned by a
single CMA region in one go from memblock.
[david@redhat.com: we can have NUMMU configs with SPARSEMEM enabled]
Link: https://lkml.kernel.org/r/6ec933b1-b3f7-41c0-95d8-e518bb87375e@redhat.com
Link: https://lkml.kernel.org/r/20250901150359.867252-23-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mm.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index f6880e3225c5..2ca1eb2db63e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -209,9 +209,15 @@ extern unsigned long sysctl_user_reserve_kbytes; extern unsigned long sysctl_admin_reserve_kbytes; #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) +bool page_range_contiguous(const struct page *page, unsigned long nr_pages); #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) #else #define nth_page(page,n) ((page) + (n)) +static inline bool page_range_contiguous(const struct page *page, + unsigned long nr_pages) +{ + return true; +} #endif /* to align the pointer to the (next) page boundary */ |