On Fri, Jun 14, 2024 at 03:30:16PM +0200, James Gowans wrote:
> Subject: [PATCH] memblocks: Move late alloc warning down to phys alloc
Nit: memblock
> If a driver/subsystem tries to do an allocation after memblocks have
> been freed and the memory handed to the buddy allocator, it will not
> actually be legal to use that allocation - the buddy allocator owns the
> memory. This is handled by the memblocks function which does allocations
> and returns virtual addresses by printing a warning and doing a kmalloc
> instead. However, the physical allocation function does not to do this
> check - callers of the physical alloc function are unprotected against
> mis-use.
Did you see such misuse or this is a theoretical issue?
> Improve the error catching here by moving the check into the physical
> allocation function which is used by the virtual addr allocation
> function.
>
> Signed-off-by: James Gowans <jgowans@xxxxxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Alex Graf <graf@xxxxxxxxx>
> ---
> mm/memblock.c | 18 +++++++++++-------
> 1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index d09136e040d3..dd4f237dc1fc 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1457,6 +1457,17 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
> align = SMP_CACHE_BYTES;
> }
>
> + /*
> + * Detect any accidental use of these APIs after slab is ready, as at
> + * this moment memblock may be deinitialized already and its
> + * internal data may be destroyed (after execution of memblock_free_all)
> + */
> + if (WARN_ON_ONCE(slab_is_available())) {
> + void *vaddr = kzalloc_node(size, GFP_NOWAIT, nid);
> +
> + return vaddr ? virt_to_phys(vaddr) : 0;
> + }
I'd move this before alignment check.
> +
> again:
> found = memblock_find_in_range_node(size, align, start, end, nid,
> flags);
> @@ -1576,13 +1587,6 @@ static void * __init memblock_alloc_internal(
> {
> phys_addr_t alloc;
>
> - /*
> - * Detect any accidental use of these APIs after slab is ready, as at
> - * this moment memblock may be deinitialized already and its
> - * internal data may be destroyed (after execution of memblock_free_all)
> - */
> - if (WARN_ON_ONCE(slab_is_available()))
> - return kzalloc_node(size, GFP_NOWAIT, nid);
>
> if (max_addr > memblock.current_limit)
> max_addr = memblock.current_limit;
> --
> 2.34.1
>
--
Sincerely yours,
Mike.
