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.
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| @@ -241,7 +241,7 @@ static ssize_t module_zstd_decompress(struct load_info *info, · 240 unmodified lines | |||
| 241 | } | 241 | } |
| 242 | 242 | ||
| 243 | wksp_size = zstd_dstream_workspace_bound(header.windowSize); | 243 | wksp_size = zstd_dstream_workspace_bound(header.windowSize); |
| 244 | wksp = kmalloc(wksp_size, GFP_KERNEL); | 244 | wksp = vmalloc(wksp_size); |
| 245 | if (!wksp) { | 245 | if (!wksp) { |
| 246 | retval = -ENOMEM; | 246 | retval = -ENOMEM; |
| 247 | goto out; | 247 | goto out; |
| @@ -284,7 +284,7 @@ static ssize_t module_zstd_decompress(struct load_info *info, · 36 unmodified lines | |||
| 284 | retval = new_size; | 284 | retval = new_size; |
| 285 | 285 | ||
| 286 | out: | 286 | out: |
| 287 | kfree(wksp); | 287 | vfree(wksp); |
| 288 | return retval; | 288 | return retval; |
| 289 | } | 289 | } |
| 290 | #else | 290 | #else |