Re: [PATCH] samples: rust: debugfs: fix excessive stack use
"Gary Guo" <[email protected]>
| Newsgroups | org.kernel.vger.rust-for-linux,dev.linux.lists.driver-core,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On Thu Jul 16, 2026 at 9:33 PM BST, Alexandre Courbot wrote: > On Thu Jul 16, 2026 at 7:41 AM PDT, Gary Guo wrote: >> From: Gary Guo <[email protected]> >> >> The current implementation creates a 4K array and move it into the box. >> Klint reports that this causes excesssive stack usage: >> >> warning: stack size of `create_file_write` is 4472 bytes, exceeds the 2048-byte limit >> --> samples/rust/rust_debugfs_scoped.rs:54:1 >> | >> 54 | / fn create_file_write( >> 55 | | mod_data: &ModuleData, >> 56 | | reader: &mut kernel::uaccess::UserSliceReader, >> 57 | | ) -> Result { >> | |___________^ >> | >> = note: the stack size is inferred from instruction `sub $0x1178,%rsp` at .text+2205 >> >> Use pin-init to create the array in-place instead. >> >> Fixes: f656279afde1 ("samples: rust: debugfs_scoped: add example for blobs") >> Signed-off-by: Gary Guo <[email protected]> >> --- >> samples/rust/rust_debugfs_scoped.rs | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/samples/rust/rust_debugfs_scoped.rs b/samples/rust/rust_debugfs_scoped.rs >> index 6a575a15a2c2..33a4a0865f5b 100644 >> --- a/samples/rust/rust_debugfs_scoped.rs >> +++ b/samples/rust/rust_debugfs_scoped.rs >> @@ -75,7 +75,7 @@ fn create_file_write( >> GFP_KERNEL, >> )?; >> } >> - let blob = KBox::pin_init(new_mutex!([0x42; SZ_4K]), GFP_KERNEL)?; >> + let blob = KBox::pin_init(new_mutex!(pin_init::init_array_from_fn(|_| 0x42)), GFP_KERNEL)?; > > Since this is a sample, do we want to specify the size explicitly as it > is arguably more readable in this case? It's not easy to specify size with `init_array_from_fn` because you need to specify additionally Init, T and E, so it'll become init_array_from_fn::<_, SZ_4K, _, _> which is ugly. Best, Gary