use PIDFD_GET_INFO ioctl when available by the8472 · Pull Request #150412 · rust-lang/rust

the8472 · 2025-12-26T23:29:02Z

This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And pidfd.{try_}wait will be able to return the exit status even after a process has been reaped. At least on newer kernels.

Tracking issue: #82971

rustbot · 2025-12-26T23:29:06Z

r? @jhpratt

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jhpratt · 2025-12-31T03:15:16Z

I'm not familiar with this area of code.

r? libs

rustbot · 2025-12-31T03:15:19Z

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jhpratt · 2026-01-04T02:52:31Z

Attempting to re-roll again

r? libs

tgross35

Two small suggestions but LGTM.

Cc @cuviper if you'd like to take a second look, since I assume you're more up on the latest pidfd developments than I am.

View changes since this review

library/std/src/sys/pal/unix/linux/pidfd.rs

the8472 · 2026-01-05T07:10:45Z

@bors r=tgross35

bors · 2026-01-05T07:10:47Z

📌 Commit bf2308f has been approved by tgross35

It is now in the queue for this repository.

use PIDFD_GET_INFO ioctl when available This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And pidfd.{try_}wait will be able to return the exit status even after a process has been reaped. At least on newer kernels. Tracking issue: rust-lang#82971

Rollup of 3 pull requests Successful merges: - #150412 (use PIDFD_GET_INFO ioctl when available) - #150668 (Unix implementation for stdio set/take/replace) - #150702 (`rust-analyzer` subtree update) r? `@ghost` `@rustbot` modify labels: rollup

matthiaskrgr · 2026-01-05T22:22:19Z

@bors r-

#150716 (comment)

the8472 · 2026-01-06T00:08:25Z

Added additional cfgs. Locally it passes x check for ohos and android.

@bors r=tgross35

This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And `pidfd.{try_}wait` will be able to return the exit status even after a process has been reaped. At least on newer kernels.

the8472 · 2026-01-06T00:52:37Z

@bors try jobs=arm-android

use PIDFD_GET_INFO ioctl when available try-job: arm-android

rust-bors · 2026-01-06T02:44:36Z

☀️ Try build successful (CI)
Build commit: db2c05c (db2c05c00f9ce5afe201427e41827cc903758986, parent: 4fa80a5e733e2202d7ca4c203c2fdfda41cfe7dc)

the8472 · 2026-01-06T02:51:29Z

@bors r=tgross35 rollup=iffy

bors · 2026-01-06T02:51:31Z

📌 Commit fa4a62b has been approved by tgross35

It is now in the queue for this repository.

use PIDFD_GET_INFO ioctl when available This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And pidfd.{try_}wait will be able to return the exit status even after a process has been reaped. At least on newer kernels. Tracking issue: rust-lang#82971

Rollup of 8 pull requests Successful merges: - #144113 (Impls and impl items inherit `dead_code` lint level of the corresponding traits and trait items) - #149880 (rustc_codegen_llvm: update alignment for double on AIX) - #150412 (use PIDFD_GET_INFO ioctl when available) - #150668 (Unix implementation for stdio set/take/replace) - #150670 (THIR pattern building: Move all `thir::Pat` creation into `rustc_mir_build::thir::pattern`) - #150695 (MGCA: pretty printing for struct expressions and tuple calls ) - #150698 (Improve comment clarity in candidate_may_shadow) - #150706 (Update wasm-component-ld) r? `@ghost` `@rustbot` modify labels: rollup

use PIDFD_GET_INFO ioctl when available This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And pidfd.{try_}wait will be able to return the exit status even after a process has been reaped. At least on newer kernels. Tracking issue: rust-lang#82971

…uwer Rollup of 11 pull requests Successful merges: - #144113 (Impls and impl items inherit `dead_code` lint level of the corresponding traits and trait items) - #148339 (naked functions: emit `.private_extern` on macos) - #149880 (rustc_codegen_llvm: update alignment for double on AIX) - #150122 (Refactor function names of `rustc_ast_lowering`) - #150412 (use PIDFD_GET_INFO ioctl when available) - #150670 (THIR pattern building: Move all `thir::Pat` creation into `rustc_mir_build::thir::pattern`) - #150695 (MGCA: pretty printing for struct expressions and tuple calls ) - #150698 (Improve comment clarity in candidate_may_shadow) - #150706 (Update wasm-component-ld) - #150707 (Fix ICE when transmute Assume field is invalid) - #150708 (Enable merge queue in new bors) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 11 pull requests Successful merges: - #144113 (Impls and impl items inherit `dead_code` lint level of the corresponding traits and trait items) - #148339 (naked functions: emit `.private_extern` on macos) - #149880 (rustc_codegen_llvm: update alignment for double on AIX) - #150122 (Refactor function names of `rustc_ast_lowering`) - #150412 (use PIDFD_GET_INFO ioctl when available) - #150670 (THIR pattern building: Move all `thir::Pat` creation into `rustc_mir_build::thir::pattern`) - #150695 (MGCA: pretty printing for struct expressions and tuple calls ) - #150698 (Improve comment clarity in candidate_may_shadow) - #150706 (Update wasm-component-ld) - #150707 (Fix ICE when transmute Assume field is invalid) - #150708 (Enable merge queue in new bors) r? `@ghost` `@rustbot` modify labels: rollup

…uwer Rollup of 10 pull requests Successful merges: - #144113 (Impls and impl items inherit `dead_code` lint level of the corresponding traits and trait items) - #149880 (rustc_codegen_llvm: update alignment for double on AIX) - #150122 (Refactor function names of `rustc_ast_lowering`) - #150412 (use PIDFD_GET_INFO ioctl when available) - #150670 (THIR pattern building: Move all `thir::Pat` creation into `rustc_mir_build::thir::pattern`) - #150695 (MGCA: pretty printing for struct expressions and tuple calls ) - #150698 (Improve comment clarity in candidate_may_shadow) - #150706 (Update wasm-component-ld) - #150707 (Fix ICE when transmute Assume field is invalid) - #150708 (Enable merge queue in new bors) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #150412 - the8472:pidfd-spawn, r=tgross35 use PIDFD_GET_INFO ioctl when available This way using pidfd_spawnp won't have to rely on procfs, avoiding an unpleasant edge-case where the child is spawned but we can't get the pid. And pidfd.{try_}wait will be able to return the exit status even after a process has been reaped. At least on newer kernels. Tracking issue: #82971

zmodem · 2026-01-13T13:38:13Z

We're seeing test failures, hitting the panic! in test_command_pidfd during testing:

 thread 'sys::pal::unix::linux::pidfd::tests::test_command_pidfd' (295684) panicked at library/std/src/sys/pal/unix/linux/pidfd/tests.rs:66:23:
 unexpected error getting pid from pidfd: Inappropriate ioctl for device (os error 25)

I think that means ioctl returned ENOTTY. This is with a Linux 6.8.0 kernel, which might be too old for this feature(?). But shouldn't the test handle that gracefully somehow?

the8472 · 2026-01-13T14:30:06Z

It's supposed to yeah but it's only checking for EINVAL and not ENOTTY, I'll submit a fix.

also handle ENOTTY ioctl errors when checking pidfd -> pid support Otherwise the std testsuite fails on older kernels. Reported in rust-lang#150412 (comment)

Rollup merge of #151072 - fix-pidfd-ioctl, r=jhpratt also handle ENOTTY ioctl errors when checking pidfd -> pid support Otherwise the std testsuite fails on older kernels. Reported in #150412 (comment)

the8472 added the O-linux Operating system: Linux label Dec 26, 2025

rustbot assigned jhpratt Dec 26, 2025

rustbot added O-unix Operating system: Unix-like S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 26, 2025

the8472 force-pushed the pidfd-spawn branch from cf9a6d6 to 9aef6ae Compare December 28, 2025 21:51

rustbot assigned tgross35 and unassigned jhpratt Jan 4, 2026

tgross35 approved these changes Jan 4, 2026

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the8472 force-pushed the pidfd-spawn branch from 9aef6ae to bf2308f Compare January 5, 2026 05:23

the8472 mentioned this pull request Jan 5, 2026

Tracking Issue for linux_pidfd #82971

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 5, 2026

JonathanBrouwer mentioned this pull request Jan 5, 2026

Rollup of 4 pull requests #150715

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matthiaskrgr mentioned this pull request Jan 5, 2026

Rollup of 3 pull requests #150716

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bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 5, 2026

the8472 force-pushed the pidfd-spawn branch 2 times, most recently from 5eba1bb to 975fda9 Compare January 6, 2026 00:05

bors added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jan 6, 2026

the8472 force-pushed the pidfd-spawn branch from 975fda9 to fa4a62b Compare January 6, 2026 00:13

rust-bors bot added a commit that referenced this pull request Jan 6, 2026

Auto merge of #150412 - the8472:pidfd-spawn, r=<try>

db2c05c

use PIDFD_GET_INFO ioctl when available try-job: arm-android

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 6, 2026

Zalathar mentioned this pull request Jan 6, 2026

Rollup of 8 pull requests #150719

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JonathanBrouwer mentioned this pull request Jan 6, 2026

Rollup of 11 pull requests #150724

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JonathanBrouwer mentioned this pull request Jan 6, 2026

Rollup of 10 pull requests #150726

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bors merged commit 3b0d35f into rust-lang:main Jan 6, 2026
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rustbot added this to the 1.94.0 milestone Jan 6, 2026

the8472 mentioned this pull request Jan 13, 2026

also handle ENOTTY ioctl errors when checking pidfd -> pid support #151072

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github-actions bot mentioned this pull request Jan 27, 2026

Toolchain upgrade to nightly-2026-01-30 flux-rs/flux#1345

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