From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 683FE202C2D for ; Tue, 4 Mar 2025 13:27:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741094852; cv=none; b=J/PGiHEO02gUScnjMYG3tJWE/8ivFImakPTbyIuMWinl/Yxp42ujG7sKcOA6crv5fes6kt8OwvI4bSF+lIgcNOzNDtlQ9K3S6SL2jwFV19guY/5t/YUW9570mkXGEr6+c5NoF0mAPTW8oH/fF2yV4jsDYjfO7iaCs3+j/BvoTNU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741094852; c=relaxed/simple; bh=/BCaftms6dDoMqUN4+KvAvXoUG57+LKdk9uP3q0SDsE=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Y3m7VLe/slVnDF0rM9R/kOSrlyyzW9NrPnbfV47dsnCIFbWkULrL654bX2Xdu9WueZ0p5wxgOhFduBqE11DN4AdwvL4tun+qVxYkVmNgqDXGTQ+Bdls5EGv0vgd37KDeXP9O0zK8MminL7CsIMcN79Cpad8puW8q6n/e4lejOAI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Yn+j0ZBu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Yn+j0ZBu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 445AEC4CEE5; Tue, 4 Mar 2025 13:27:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741094850; bh=/BCaftms6dDoMqUN4+KvAvXoUG57+LKdk9uP3q0SDsE=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=Yn+j0ZBuzrXZgFUSYoAbTwoN9UAdTgWX2To/dx4AzcMl/sdrDxABZFUXRdHTkvnUv 1vEPwIERyDeqUfjxYkGycmVH/rmTotIbz3kSo8yDLO62IdlHP3eE0u8UFkIGpVrFWL f2Fog1AADaiW0byhXDbYBhwxtAsKPAzxQy13/DCMfXsTEEp43tPdKUkNtI+wWTvkDE WgG+q3iHoFuomP0oSiXnvFM4V0xXNfnz7wJnpLX34OHgmsG28xvRlOzXmiFsi7qILL CMrVnDblJ3Pm+DHhprXu1iX98nkjy3pgwoU6KwF9W2RShV9yTb08zi+GBc1+hfzLyE IKzT7l8i30eGg== Message-ID: Subject: Re: [PATCH v2 06/15] pidfs: allow to retrieve exit information From: Jeff Layton To: Christian Brauner , Oleg Nesterov Cc: linux-fsdevel@vger.kernel.org, Lennart Poettering , Daan De Meyer , Mike Yuan Date: Tue, 04 Mar 2025 08:27:29 -0500 In-Reply-To: <20250304-work-pidfs-kill_on_last_close-v2-6-44fdacfaa7b7@kernel.org> References: <20250304-work-pidfs-kill_on_last_close-v2-0-44fdacfaa7b7@kernel.org> <20250304-work-pidfs-kill_on_last_close-v2-6-44fdacfaa7b7@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf CBYyUE8QJpvTZyfUHNYldXlrjO6n5MdOempLqWpfOmcGkwnyNRBR46g/jf8KnPRwXs509yAqDB6sE LZH+yWr9LQZEwARAQABtCVKZWZmIExheXRvbiA8amxheXRvbkBwb29jaGllcmVkcy5uZXQ+iQI7BB MBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUCTpXWPAIZAQAKCRAADmhBGVaCFc65D/4 gBLNMHopQYgG/9RIM3kgFCCQV0pLv0hcg1cjr+bPI5f1PzJoOVi9s0wBDHwp8+vtHgYhM54yt43uI 7Htij0RHFL5eFqoVT4TSfAg2qlvNemJEOY0e4daljjmZM7UtmpGs9NN0r9r50W82eb5Kw5bc/r0km R/arUS2st+ecRsCnwAOj6HiURwIgfDMHGPtSkoPpu3DDp/cjcYUg3HaOJuTjtGHFH963B+f+hyQ2B rQZBBE76ErgTDJ2Db9Ey0kw7VEZ4I2nnVUY9B5dE2pJFVO5HJBMp30fUGKvwaKqYCU2iAKxdmJXRI ONb7dSde8LqZahuunPDMZyMA5+mkQl7kpIpR6kVDIiqmxzRuPeiMP7O2FCUlS2DnJnRVrHmCljLkZ Wf7ZUA22wJpepBligemtSRSbqCyZ3B48zJ8g5B8xLEntPo/NknSJaYRvfEQqGxgk5kkNWMIMDkfQO lDSXZvoxqU9wFH/9jTv1/6p8dHeGM0BsbBLMqQaqnWiVt5mG92E1zkOW69LnoozE6Le+12DsNW7Rj iR5K+27MObjXEYIW7FIvNN/TQ6U1EOsdxwB8o//Yfc3p2QqPr5uS93SDDan5ehH59BnHpguTc27Xi QQZ9EGiieCUx6Zh2ze3X2UW9YNzE15uKwkkuEIj60NvQRmEDfweYfOfPVOueC+iFifbQgSmVmZiBM YXl0b24gPGpsYXl0b25AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6V0q0CGwMGCwkIBwMCBhUIAgkKC wQWAgMBAh4BAheAAAoJEAAOaEEZVoIViKUQALpvsacTMWWOd7SlPFzIYy2/fjvKlfB/Xs4YdNcf9q LqF+lk2RBUHdR/dGwZpvw/OLmnZ8TryDo2zXVJNWEEUFNc7wQpl3i78r6UU/GUY/RQmOgPhs3epQC 3PMJj4xFx+VuVcf/MXgDDdBUHaCTT793hyBeDbQuciARDJAW24Q1RCmjcwWIV/pgrlFa4lAXsmhoa c8UPc82Ijrs6ivlTweFf16VBc4nSLX5FB3ls7S5noRhm5/Zsd4PGPgIHgCZcPgkAnU1S/A/rSqf3F LpU+CbVBDvlVAnOq9gfNF+QiTlOHdZVIe4gEYAU3CUjbleywQqV02BKxPVM0C5/oVjMVx3bri75n1 TkBYGmqAXy9usCkHIsG5CBHmphv9MHmqMZQVsxvCzfnI5IO1+7MoloeeW/lxuyd0pU88dZsV/riHw 87i2GJUJtVlMl5IGBNFpqoNUoqmvRfEMeXhy/kUX4Xc03I1coZIgmwLmCSXwx9MaCPFzV/dOOrju2 xjO+2sYyB5BNtxRqUEyXglpujFZqJxxau7E0eXoYgoY9gtFGsspzFkVNntamVXEWVVgzJJr/EWW0y +jNd54MfPRqH+eCGuqlnNLktSAVz1MvVRY1dxUltSlDZT7P2bUoMorIPu8p7ZCg9dyX1+9T6Muc5d Hxf/BBP/ir+3e8JTFQBFOiLNdFtB9KZWZmIExheXRvbiA8amxheXRvbkBzYW1iYS5vcmc+iQI4BBM BAgAiBQJOldK9AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAADmhBGVaCFWgWD/0ZRi4h N9FK2BdQs9RwNnFZUr7JidAWfCrs37XrA/56olQl3ojn0fQtrP4DbTmCuh0SfMijB24psy1GnkPep naQ6VRf7Dxg/Y8muZELSOtsv2CKt3/02J1BBitrkkqmHyni5fLLYYg6fub0T/8Kwo1qGPdu1hx2BQ RERYtQ/S5d/T0cACdlzi6w8rs5f09hU9Tu4qV1JLKmBTgUWKN969HPRkxiojLQziHVyM/weR5Reu6 FZVNuVBGqBD+sfk/c98VJHjsQhYJijcsmgMb1NohAzwrBKcSGKOWJToGEO/1RkIN8tqGnYNp2G+aR 685D0chgTl1WzPRM6mFG1+n2b2RR95DxumKVpwBwdLPoCkI24JkeDJ7lXSe3uFWISstFGt0HL8Eew P8RuGC8s5h7Ct91HMNQTbjgA+Vi1foWUVXpEintAKgoywaIDlJfTZIl6Ew8ETN/7DLy8bXYgq0Xzh aKg3CnOUuGQV5/nl4OAX/3jocT5Cz/OtAiNYj5mLPeL5z2ZszjoCAH6caqsF2oLyAnLqRgDgR+wTQ T6gMhr2IRsl+cp8gPHBwQ4uZMb+X00c/Amm9VfviT+BI7B66cnC7Zv6Gvmtu2rEjWDGWPqUgccB7h dMKnKDthkA227/82tYoFiFMb/NwtgGrn5n2vwJyKN6SEoygGrNt0SI84y6hEVbQlSmVmZiBMYXl0b 24gPGpsYXl0b25AcHJpbWFyeWRhdGEuY29tPokCOQQTAQIAIwUCU4xmKQIbAwcLCQgHAwIBBhUIAg kKCwQWAgMBAh4BAheAAAoJEAAOaEEZVoIV1H0P/j4OUTwFd7BBbpoSp695qb6HqCzWMuExsp8nZjr uymMaeZbGr3OWMNEXRI1FWNHMtcMHWLP/RaDqCJil28proO+PQ/yPhsr2QqJcW4nr91tBrv/MqItu AXLYlsgXqp4BxLP67bzRJ1Bd2x0bWXurpEXY//VBOLnODqThGEcL7jouwjmnRh9FTKZfBDpFRaEfD FOXIfAkMKBa/c9TQwRpx2DPsl3eFWVCNuNGKeGsirLqCxUg5kWTxEorROppz9oU4HPicL6rRH22Ce 6nOAON2vHvhkUuO3GbffhrcsPD4DaYup4ic+DxWm+DaSSRJ+e1yJvwi6NmQ9P9UAuLG93S2MdNNbo sZ9P8k2mTOVKMc+GooI9Ve/vH8unwitwo7ORMVXhJeU6Q0X7zf3SjwDq2lBhn1DSuTsn2DbsNTiDv qrAaCvbsTsw+SZRwF85eG67eAwouYk+dnKmp1q57LDKMyzysij2oDKbcBlwB/TeX16p8+LxECv51a sjS9TInnipssssUDrHIvoTTXWcz7Y5wIngxDFwT8rPY3EggzLGfK5Zx2Q5S/N0FfmADmKknG/D8qG IcJE574D956tiUDKN4I+/g125ORR1v7bP+OIaayAvq17RP+qcAqkxc0x8iCYVCYDouDyNvWPGRhbL UO7mlBpjW9jK9e2fvZY9iw3QzIPGKtClKZWZmIExheXRvbiA8amVmZi5sYXl0b25AcHJpbWFyeWRh dGEuY29tPokCOQQTAQIAIwUCU4xmUAIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEAAOa EEZVoIVzJoQALFCS6n/FHQS+hIzHIb56JbokhK0AFqoLVzLKzrnaeXhE5isWcVg0eoV2oTScIwUSU apy94if69tnUo4Q7YNt8/6yFM6hwZAxFjOXR0ciGE3Q+Z1zi49Ox51yjGMQGxlakV9ep4sV/d5a50 M+LFTmYSAFp6HY23JN9PkjVJC4PUv5DYRbOZ6Y1+TfXKBAewMVqtwT1Y+LPlfmI8dbbbuUX/kKZ5d dhV2736fgyfpslvJKYl0YifUOVy4D1G/oSycyHkJG78OvX4JKcf2kKzVvg7/Rnv+AueCfFQ6nGwPn 0P91I7TEOC4XfZ6a1K3uTp4fPPs1Wn75X7K8lzJP/p8lme40uqwAyBjk+IA5VGd+CVRiyJTpGZwA0 jwSYLyXboX+Dqm9pSYzmC9+/AE7lIgpWj+3iNisp1SWtHc4pdtQ5EU2SEz8yKvDbD0lNDbv4ljI7e flPsvN6vOrxz24mCliEco5DwhpaaSnzWnbAPXhQDWb/lUgs/JNk8dtwmvWnqCwRqElMLVisAbJmC0 BhZ/Ab4sph3EaiZfdXKhiQqSGdK4La3OTJOJYZphPdGgnkvDV9Pl1QZ0ijXQrVIy3zd6VCNaKYq7B AKidn5g/2Q8oio9Tf4XfdZ9dtwcB+bwDJFgvvDYaZ5bI3ln4V3EyW5i2NfXazz/GA/I/ZtbsigCFc 8ftCBKZWZmIExheXRvbiA8amxheXRvbkBrZXJuZWwub3JnPokCOAQTAQIAIgUCWe8u6AIbAwYLCQg HAwIGFQgCCQoLBBYCAwECHgECF4AACgkQAA5oQRlWghUuCg/+Lb/xGxZD2Q1oJVAE37uW308UpVSD 2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-03-04 at 10:41 +0100, Christian Brauner wrote: > Some tools like systemd's jounral need to retrieve the exit and cgroup > information after a process has already been reaped. This can e.g., > happen when retrieving a pidfd via SCM_PIDFD or SCM_PEERPIDFD. >=20 > Signed-off-by: Christian Brauner > --- > fs/pidfs.c | 88 ++++++++++++++++++++++++++++++++++++----= ------ > include/uapi/linux/pidfd.h | 3 +- > kernel/exit.c | 2 +- > 3 files changed, 73 insertions(+), 20 deletions(-) >=20 > diff --git a/fs/pidfs.c b/fs/pidfs.c > index 258e1c13ee56..11744d7fe177 100644 > --- a/fs/pidfs.c > +++ b/fs/pidfs.c > @@ -36,7 +36,8 @@ struct pidfs_exit_info { > }; > =20 > struct pidfs_inode { > - struct pidfs_exit_info exit_info; > + struct pidfs_exit_info __pei; > + struct pidfs_exit_info *exit_info; > struct inode vfs_inode; > }; > =20 > @@ -228,17 +229,28 @@ static __poll_t pidfd_poll(struct file *file, struc= t poll_table_struct *pts) > return poll_flags; > } > =20 > -static long pidfd_info(struct task_struct *task, unsigned int cmd, unsig= ned long arg) > +static inline bool current_in_pidns(struct pid *pid) > +{ > + const struct pid_namespace *ns =3D task_active_pid_ns(current); > + > + if (ns->level <=3D pid->level) > + return pid->numbers[ns->level].ns =3D=3D ns; > + > + return false; > +} > + > +static long pidfd_info(struct file *file, unsigned int cmd, unsigned lon= g arg) > { > struct pidfd_info __user *uinfo =3D (struct pidfd_info __user *)arg; > + struct pid *pid =3D pidfd_pid(file); > size_t usize =3D _IOC_SIZE(cmd); > struct pidfd_info kinfo =3D {}; > + struct pidfs_exit_info *exit_info; > + struct inode *inode =3D file_inode(file); > struct user_namespace *user_ns; > + struct task_struct *task; > const struct cred *c; > __u64 mask; > -#ifdef CONFIG_CGROUPS > - struct cgroup *cgrp; > -#endif > =20 > if (!uinfo) > return -EINVAL; > @@ -248,6 +260,37 @@ static long pidfd_info(struct task_struct *task, uns= igned int cmd, unsigned long > if (copy_from_user(&mask, &uinfo->mask, sizeof(mask))) > return -EFAULT; > =20 > + task =3D get_pid_task(pid, PIDTYPE_PID); > + if (!task) { > + if (!(mask & PIDFD_INFO_EXIT)) > + return -ESRCH; > + > + if (!current_in_pidns(pid)) > + return -ESRCH; > + } > + > + if (mask & PIDFD_INFO_EXIT) { > + exit_info =3D READ_ONCE(pidfs_i(inode)->exit_info); > + if (exit_info) { > +#ifdef CONFIG_CGROUPS > + kinfo.cgroupid =3D exit_info->cgroupid; > + kinfo.mask |=3D PIDFD_INFO_EXIT | PIDFD_INFO_CGROUPID; > +#endif > + kinfo.exit_code =3D exit_info->exit_code; > + } > + } > + > + /* > + * If the task has already been reaped only exit information > + * can be provided. It's entirely possible that the task has > + * already been reaped but we managed to grab a reference to it > + * before that. So a full set of information about @task doesn't > + * mean it hasn't been waited upon. Similarly, a full set of > + * information doesn't mean that the task hasn't already exited. > + */ > + if (!task) > + goto copy_out; > + > c =3D get_task_cred(task); > if (!c) > return -ESRCH; > @@ -267,11 +310,15 @@ static long pidfd_info(struct task_struct *task, un= signed int cmd, unsigned long > put_cred(c); > =20 > #ifdef CONFIG_CGROUPS > - rcu_read_lock(); > - cgrp =3D task_dfl_cgroup(task); > - kinfo.cgroupid =3D cgroup_id(cgrp); > - kinfo.mask |=3D PIDFD_INFO_CGROUPID; > - rcu_read_unlock(); > + if (!kinfo.cgroupid) { > + struct cgroup *cgrp; > + > + rcu_read_lock(); > + cgrp =3D task_dfl_cgroup(task); > + kinfo.cgroupid =3D cgroup_id(cgrp); > + kinfo.mask |=3D PIDFD_INFO_CGROUPID; > + rcu_read_unlock(); > + } > #endif > =20 > /* > @@ -291,6 +338,7 @@ static long pidfd_info(struct task_struct *task, unsi= gned int cmd, unsigned long > if (kinfo.pid =3D=3D 0 || kinfo.tgid =3D=3D 0 || (kinfo.ppid =3D=3D 0 &= & kinfo.pid !=3D 1)) > return -ESRCH; > =20 > +copy_out: > /* > * If userspace and the kernel have the same struct size it can just > * be copied. If userspace provides an older struct, only the bits that > @@ -325,7 +373,6 @@ static long pidfd_ioctl(struct file *file, unsigned i= nt cmd, unsigned long arg) > { > struct task_struct *task __free(put_task) =3D NULL; > struct nsproxy *nsp __free(put_nsproxy) =3D NULL; > - struct pid *pid =3D pidfd_pid(file); > struct ns_common *ns_common =3D NULL; > struct pid_namespace *pid_ns; > =20 > @@ -340,13 +387,13 @@ static long pidfd_ioctl(struct file *file, unsigned= int cmd, unsigned long arg) > return put_user(file_inode(file)->i_generation, argp); > } > =20 > - task =3D get_pid_task(pid, PIDTYPE_PID); > - if (!task) > - return -ESRCH; > - > /* Extensible IOCTL that does not open namespace FDs, take a shortcut *= / > if (_IOC_NR(cmd) =3D=3D _IOC_NR(PIDFD_GET_INFO)) > - return pidfd_info(task, cmd, arg); > + return pidfd_info(file, cmd, arg); > + > + task =3D get_pid_task(pidfd_pid(file), PIDTYPE_PID); > + if (!task) > + return -ESRCH; > =20 > if (arg) > return -EINVAL; > @@ -479,10 +526,12 @@ void pidfs_exit(struct task_struct *tsk) > { > struct dentry *dentry; > =20 > + might_sleep(); > + > dentry =3D stashed_dentry_get(&task_pid(tsk)->stashed); > if (dentry) { > struct inode *inode =3D d_inode(dentry); > - struct pidfs_exit_info *exit_info =3D &pidfs_i(inode)->exit_info; > + struct pidfs_exit_info *exit_info =3D &pidfs_i(inode)->__pei; > #ifdef CONFIG_CGROUPS > struct cgroup *cgrp; > =20 > @@ -493,6 +542,8 @@ void pidfs_exit(struct task_struct *tsk) > #endif > exit_info->exit_code =3D tsk->exit_code; > =20 > + /* Ensure that PIDFD_GET_INFO sees either all or nothing. */ > + smp_store_release(&pidfs_i(inode)->exit_info, &pidfs_i(inode)->__pei); > dput(dentry); > } > } > @@ -560,7 +611,8 @@ static struct inode *pidfs_alloc_inode(struct super_b= lock *sb) > if (!pi) > return NULL; > =20 > - memset(&pi->exit_info, 0, sizeof(pi->exit_info)); > + memset(&pi->__pei, 0, sizeof(pi->__pei)); > + pi->exit_info =3D NULL; > =20 > return &pi->vfs_inode; > } > diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h > index e0abd0b18841..e5966f1a7743 100644 > --- a/include/uapi/linux/pidfd.h > +++ b/include/uapi/linux/pidfd.h > @@ -20,6 +20,7 @@ > #define PIDFD_INFO_PID (1UL << 0) /* Always returned, even if not requ= ested */ > #define PIDFD_INFO_CREDS (1UL << 1) /* Always returned, even if not req= uested */ > #define PIDFD_INFO_CGROUPID (1UL << 2) /* Always returned if available,= even if not requested */ > +#define PIDFD_INFO_EXIT (1UL << 3) /* Always returned if available, ev= en if not requested */ > =20 > #define PIDFD_INFO_SIZE_VER0 64 /* sizeof first published struct */ > =20 > @@ -86,7 +87,7 @@ struct pidfd_info { > __u32 sgid; > __u32 fsuid; > __u32 fsgid; > - __u32 spare0[1]; > + __s32 exit_code; > }; > =20 > #define PIDFS_IOCTL_MAGIC 0xFF > diff --git a/kernel/exit.c b/kernel/exit.c > index 98d292120296..9916305e34d3 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -250,12 +250,12 @@ void release_task(struct task_struct *p) > dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); > rcu_read_unlock(); > =20 > + pidfs_exit(p); > cgroup_release(p); > =20 > write_lock_irq(&tasklist_lock); > ptrace_release_task(p); > thread_pid =3D get_pid(p->thread_pid); > - pidfs_exit(p); Why move this after you just added it? > __exit_signal(p); > =20 > /* >=20 Everything else looks fine though. Assuming you fix the nit above, you can add: Reviewed-by: Jeff Layton