On Tue, Aug 29, 2023 at 02:05:08PM +0200, Andrea Righi wrote:
> Using kmalloc() to allocate the decompression workspace for zstd may
> trigger the following warning when large modules are loaded (i.e., xfs):
>
> [ 2.961884] WARNING: CPU: 1 PID: 254 at mm/page_alloc.c:4453 __alloc_pages+0x2c3/0x350
> ...
> [ 2.989033] Call Trace:
> [ 2.989841] <TASK>
> [ 2.990614] ? show_regs+0x6d/0x80
> [ 2.991573] ? __warn+0x89/0x160
> [ 2.992485] ? __alloc_pages+0x2c3/0x350
> [ 2.993520] ? report_bug+0x17e/0x1b0
> [ 2.994506] ? handle_bug+0x51/0xa0
> [ 2.995474] ? exc_invalid_op+0x18/0x80
> [ 2.996469] ? asm_exc_invalid_op+0x1b/0x20
> [ 2.997530] ? module_zstd_decompress+0xdc/0x2a0
> [ 2.998665] ? __alloc_pages+0x2c3/0x350
> [ 2.999695] ? module_zstd_decompress+0xdc/0x2a0
> [ 3.000821] __kmalloc_large_node+0x7a/0x150
> [ 3.001920] __kmalloc+0xdb/0x170
> [ 3.002824] module_zstd_decompress+0xdc/0x2a0
> [ 3.003857] module_decompress+0x37/0xc0
> [ 3.004688] init_module_from_file+0xd0/0x100
> [ 3.005668] idempotent_init_module+0x11c/0x2b0
> [ 3.006632] __x64_sys_finit_module+0x64/0xd0
> [ 3.007568] do_syscall_64+0x59/0x90
> [ 3.008373] ? ksys_read+0x73/0x100
> [ 3.009395] ? exit_to_user_mode_prepare+0x30/0xb0
> [ 3.010531] ? syscall_exit_to_user_mode+0x37/0x60
> [ 3.011662] ? do_syscall_64+0x68/0x90
> [ 3.012511] ? do_syscall_64+0x68/0x90
> [ 3.013364] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>
> However, continuous physical memory does not seem to be required in
> module_zstd_decompress(), so use vmalloc() instead, to prevent the
> warning and avoid potential failures at loading compressed modules.
>
> Fixes: 169a58ad824d ("module/decompress: Support zstd in-kernel decompression")
> Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
> ---
> kernel/module/decompress.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
> index 8a5d6d63b06c..87440f714c0c 100644
> --- a/kernel/module/decompress.c
> +++ b/kernel/module/decompress.c
> @@ -241,7 +241,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
> }
>
> wksp_size = zstd_dstream_workspace_bound(header.windowSize);
> - wksp = kmalloc(wksp_size, GFP_KERNEL);
> + wksp = vmalloc(wksp_size);
> if (!wksp) {
> retval = -ENOMEM;
> goto out;
> @@ -284,7 +284,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
> retval = new_size;
>
> out:
> - kfree(wksp);
> + vfree(wksp);
> return retval;
Thanks! Applied and queued up.
Luis
