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mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly

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set_area_direct_map() always updates direct map alias permissions in
single page increments.

For HUGE_VMAP areas it's suboptimal.  Not only the loop in
set_area_direct_map() needlessly has more iterations (e.g times 512 on
x86), but it also causes fragmentation of the direct map that could be
avoided for the HUGE_VMAP areas populated with large pages.

All pages in an area are always of the same order: either same-order large
pages when VM_ALLOW_HUGE_VMAP is set and all huge pages were successfully
allocated, or order-0 page when VM_ALLOW_HUGE_VMAP is cleared or when huge
pages allocation fails and fallback path is taken.

Instead of updating the direct map permissions for every order-0 page in
an area, use the area's page_order as the loop increment and update the
large pages in one call to set_direct_map_{invalid,default}_noflush().

Link: https://lore.kernel.org/20260903-execmem-set-vm-perms-v0-2-v3-4-949b64a9f755@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
This commit is contained in:
Mike Rapoport (Microsoft) 2026-09-03 12:28:30 +03:00 committed by Andrew Morton
parent 1f73dfdeb9
commit 86dc0280b8
1 changed files with 8 additions and 5 deletions
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13
mm/vmalloc.c
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@ -3361,12 +3361,15 @@ static inline void set_area_direct_map(const struct vm_struct *area,
int (*set_direct_map)(struct page *page,
unsigned int nr))
{
unsigned long i;
unsigned int nr = (1U << vm_area_page_order(area));
/* HUGE_VMALLOC passes small pages to set_direct_map */
for (i = 0; i < area->nr_pages; i++)
if (page_address(area->pages[i]))
set_direct_map(area->pages[i], 1);
for (unsigned long i = 0; i < area->nr_pages; i += nr) {
if (page_address(area->pages[i])) {
int err = set_direct_map(area->pages[i], nr);
WARN_ON_ONCE(err);
}
}
}
/*