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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47d06e5sm1167625566b.63.2025.02.05.11.32.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:32:54 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v4 1/5] exit: perform add_device_randomness() without tasklist_lock Date: Wed, 5 Feb 2025 20:32:17 +0100 Message-ID: <20250205193221.402150-2-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250205193221.402150-1-mjguzik@gmail.com> References: <20250205193221.402150-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Parallel calls to add_device_randomness() contend on their own. The clone side aleady runs outside of tasklist_lock, which in turn means any caller on the exit side extends the tasklist_lock hold time while contending on the random-private lock. Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- kernel/exit.c | 6 +++--- scripts/selinux/genheaders/genheaders | Bin 90112 -> 0 bytes 2 files changed, 3 insertions(+), 3 deletions(-) delete mode 100755 scripts/selinux/genheaders/genheaders diff --git a/kernel/exit.c b/kernel/exit.c index 3485e5fc499e..c79b41509cd3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -174,9 +174,6 @@ static void __exit_signal(struct task_struct *tsk) sig->curr_target =3D next_thread(tsk); } =20 - add_device_randomness((const void*) &tsk->se.sum_exec_runtime, - sizeof(unsigned long long)); - /* * Accumulate here the counters for all threads as they die. We could * skip the group leader because it is the last user of signal_struct, @@ -278,6 +275,9 @@ void release_task(struct task_struct *p) write_unlock_irq(&tasklist_lock); proc_flush_pid(thread_pid); put_pid(thread_pid); + add_device_randomness(&p->se.sum_exec_runtime, + sizeof(p->se.sum_exec_runtime)); + free_pids(post.pids); release_thread(p); put_task_struct_rcu_user(p); =20 diff --git a/scripts/selinux/genheaders/genheaders b/scripts/selinux/genhea= ders/genheaders deleted file mode 100755 index 3fc32a664a7930b12a38d02449aec78d49690dfe..000000000000000000000000000= 0000000000000 GIT binary patch literal 0 HcmV?d00001 literal 90112 zcmeI54VYWidFQXqM}!HsAV3BA;1X~VGz`MnRD8IRv5n=3D#7zLYDVcSUZjK)$tBMC`k z%cLnHP^yXRL`~8@lP2BHlcn8hyWI-frUOqCluw3sHxX$*)FdTJmIS#ZsnShSku1!< z=3Dic`(>;7Xu*(8vziNu57dw%zvbI*P6@7#MeGt#|t>y8^&u2^B=3Db&~ZfmMPUg;gX21 zh{TW9iCAIl3@c(?V75G0Y}Pybz2YuevQ`@Q68ZnJ^e3mU`L{!u9%h~AW!jm#{CcH;WAUBG z;qN*Q|DteP{^!@70*=3D-HHOJxi9*6(Ca9jT8*Es@?)&Et;;g=3DkT|ITrE{W zo=3Dl8q_F0p~blOT+vSq7OE>6r8tjT;Koil|g35mqyP~AjAv>s2C%Bf;GF`deqY7^;V z(QKuXN=3D#;Rsj2K8Y13F}zGzL3PvuK#YqBs?9=3D9eB6tm^D)RlF)yctQVoXzJf)2Epk zS6kb5Y`X77Jj_Se7r z`!dZ=3DwjR>*%=3Du>hN!G`;{E}?;4707rq-3X zK5<*?`@ZJw|Mbtfokr+A0R;rRZgav$-Bl>3Q)M0tSt zCzad8A6FhE{x8Z~#Gh8)Ccfg+?zlU|ga7FAF7Z>fevkNS<$dDkDz~2W=3DI0g4eZ+rJ zxu5v9&$#Ua#4p$SHu0;K2Z_I0d5HLHl!uAmqC7(UHsw*`DdjQZ8Rc=3D}Ips;>`;}*i z|EBT+@wX|j5dS^pRpRecUL*b|%Im}%%IAoGNclYRN0l!Se@uCU_!pHg5`RK@llZrl zFA-l>-XVS(d?tRD@*eRE!Mk2>|3N+M6TeF9TSvV0uUGCP9#!rqzDs$4_#Wjp@!OSK z|Ki>5Ta^2V*OdE-zg>BN_=3D+y%Ip8b%KgM2Q63$tLRjnT({w?KE;(g^Y;wyEWapI>dPZB>H`}GZPesF&n zB!0fu4-wz2^CC=3Dq&*$BKBh2-FBT5|ki4nK4U&PPWJS2%DpBduFXMuQ7`>zncLV1<=3D zRmy9`Hz=3DT&e8^qtBe3AI1@+R?p%9n`4hZgaY)^8KPQ+bDY zO?j92obn#=3D`;_;I|Bdp{H@$v#l!uAK&j@k&86^%sW6aghIC1!yBo03_#NlUwIQ*;- zho4pA@Uuo7e%6V@&pG1obDlW-Tp$iV8^qz~B60ZHBo059h{MkoaroIL4nI4@;b)gP z{Ol2jpMB!+)B2Xzx2F2$BmSszKk?5h4-mgk&yzOs$F+Wh_!G*b#Gh0i`&aKcpHdzt zj(L$Jj(L$Gj(JgFuJfWo9P^?|9P^?^9P^@19P?t1IOfGXam$h+|&#iDO<^J+BX#7e3;c7k=3DWH7Xjj!7fIsZ zQQtDe;ahJaPE8Kpeg`h{Lx<;_$6W9KJ0Phi@(7 z@U2Z8zIBMhw=3DQw`)*}wz`o!Uz^=3D+>|@XbdYzWIs6w*YbYW)p{RLE`YOK>Qi?twJ2W zRf)s58gckmXa1PG|8vCQ+dOgjwm=3D-dHHgEvMdI+SNgTc{5r=3DOr;_$6a9KLmk!?!MR z_|_v1-}=3DPioAqyAf8d*sIDGRHhi?Jm@XaO;--5*9TZlM(3loQLRpO`W&&g}V;aikx-;UE=3DVqM;yNOiNiPR ze|!CbZ$9Gi%}*S@1&G5pn>c(65{GXg;_xj@9KJ<}!?!4L_*N(GSKsD{!?$_j@NI!O zd}}aQ-xi6(wc*y5QlGF;_$6U9KQ95!#C@@UVpMWAAQ72%KgO8R~{gKp>msePg=3DITS6IDF_3hYwxi@S#T> zKJ{D~8XKS|>7Cqo?m6o|v0 z7V&#^{B7d!q(dB@bcw^09&`1iPaK|DefK!vxWf}4ad_e<4o?Ea;fYNgo&<@*lMr!u z5+)8$BE;cIlsG(z5r-#n;_xI%9G+x|!;=3DDWcv2w_PpZV>NryQ8E~rZ!+wBp@c6(2I zk1zfnsZab}>Y??0Z~gaz|G>-NuiQr*-uj8d+W>KRYcp4GgT&!&h&a3r6Nk4E;_x;~ z9Nxx=3D!`nDO+7ye6WebhahqI5Mr)Ago(q42yyrjB@Q2A#Nk7nIDAMFhYuOz@S#8)K2(UqhbnRS zP$Lc>>crv09C7$CPaHlh5Qh&9;_zXSIDD|5@%r$v`Vb@zA40_8Lzp;xh%i?lqQv1t zj5vIV6Ne8;;_x9u96l6?!-ooS_)sMdA8N$mL!CH$m?I7!=3D840H1>*3bK^#6T5{C~> z;_zXKID7~_>-FL9)rT-~_z)ouAELzJLyWol5GM{FlEmRdhB$mE5Qh&H;_#tL96r>D z!-qO?_%KHtKFkw`4-3TMLxVVcSR@V~n#AG55^?y@A`Tzg#Nk7S_&=3D);k!7zZPb!ZR zhbJ-O@FY$go+O#8CmG`Kq(B^=3DREWcqDsgyHBMwjM#No*tadRP@(OX}tx6nu zs}V=3Du>co+^IpWCMJaOc0fjIKkAdb8(5=3DY*e#9yWRTRq8}hxN*9#F2+OapYl+IPx%0 z9C=3DtEjyyDoBM*zjk%uO6)UHED}c^ zn#7TZCF00Ki#YPoCXPJJpW@x$>vew@h~qlaAdYb^62~~3%yphF5l4Pn#F3viaU8D> zaa>2b#Bm+z5yy3;PaM|~%X|QD=3D)8*Sh>tj~BYxtzjs%F~I${&YbtFg}*O3r$Tt~vh zaUF>e$8{u1d~h8h{yOy`PW;!DH;8AHFA|48P2%upi8%aeF;{=3Du#NkheIQ;1nhd({y z@TX54{#Y;a`T&1?#Nm&hIQ$6^hd(xP_!A@!e?r9JPnbCTi4ccBQR46?MjZaciNl{H zarl!V4u6`&?^J)5h{K;2aro0F4u3k#)t@eL_|qc}fBMAXkLC0F0DpYM;g6p<{0R_; 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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47d06e5sm1167625566b.63.2025.02.05.11.32.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:32:58 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v4 2/5] exit: hoist get_pid() in release_task() outside of tasklist_lock Date: Wed, 5 Feb 2025 20:32:18 +0100 Message-ID: <20250205193221.402150-3-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250205193221.402150-1-mjguzik@gmail.com> References: <20250205193221.402150-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" reduces hold time as get_pid() contains an atomic Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- kernel/exit.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/exit.c b/kernel/exit.c index c79b41509cd3..b5c0cbc6bdfb 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -248,9 +248,10 @@ void release_task(struct task_struct *p) =20 cgroup_release(p); 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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47d06e5sm1167625566b.63.2025.02.05.11.32.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:33:01 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v4 3/5] pid: sprinkle tasklist_lock asserts Date: Wed, 5 Feb 2025 20:32:19 +0100 Message-ID: <20250205193221.402150-4-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250205193221.402150-1-mjguzik@gmail.com> References: <20250205193221.402150-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- kernel/pid.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/pid.c b/kernel/pid.c index 924084713be8..2ae872f689a7 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -339,17 +339,23 @@ static struct pid **task_pid_ptr(struct task_struct *= task, enum pid_type type) */ void attach_pid(struct task_struct *task, enum pid_type type) { - struct pid *pid =3D *task_pid_ptr(task, type); + struct pid *pid; + + lockdep_assert_held_write(&tasklist_lock); + + pid =3D *task_pid_ptr(task, type); hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]); } =20 static void __change_pid(struct task_struct *task, enum pid_type type, struct pid *new) { - struct pid **pid_ptr =3D task_pid_ptr(task, type); - struct pid *pid; + struct pid **pid_ptr, *pid; int tmp; =20 + lockdep_assert_held_write(&tasklist_lock); + + pid_ptr =3D task_pid_ptr(task, type); pid =3D *pid_ptr; =20 hlist_del_rcu(&task->pid_links[type]); @@ -386,6 +392,8 @@ void exchange_tids(struct task_struct *left, struct tas= k_struct *right) struct hlist_head *head1 =3D &pid1->tasks[PIDTYPE_PID]; struct hlist_head *head2 =3D &pid2->tasks[PIDTYPE_PID]; =20 + lockdep_assert_held_write(&tasklist_lock); + /* Swap the single entry tid lists */ hlists_swap_heads_rcu(head1, head2); =20 @@ -403,6 +411,7 @@ void transfer_pid(struct task_struct *old, struct task_= struct *new, enum pid_type type) { WARN_ON_ONCE(type =3D=3D PIDTYPE_PID); 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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47d06e5sm1167625566b.63.2025.02.05.11.33.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:33:04 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v4 4/5] pid: perform free_pid() calls outside of tasklist_lock Date: Wed, 5 Feb 2025 20:32:20 +0100 Message-ID: <20250205193221.402150-5-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250205193221.402150-1-mjguzik@gmail.com> References: <20250205193221.402150-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As the clone side already executes pid allocation with only pidmap_lock held, issuing free_pid() while still holding tasklist_lock exacerbates total hold time of the latter. The pid array is smuggled through newly added release_task_post struct so that any extra things want to get moved out have means to do it. Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- include/linux/pid.h | 7 ++++--- kernel/exit.c | 27 +++++++++++++++++++-------- kernel/pid.c | 44 ++++++++++++++++++++++---------------------- kernel/sys.c | 14 +++++++++----- 4 files changed, 54 insertions(+), 38 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index 98837a1ff0f3..311ecebd7d56 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -101,9 +101,9 @@ extern struct pid *get_task_pid(struct task_struct *tas= k, enum pid_type type); * these helpers must be called with the tasklist_lock write-held. */ extern void attach_pid(struct task_struct *task, enum pid_type); -extern void detach_pid(struct task_struct *task, enum pid_type); -extern void change_pid(struct task_struct *task, enum pid_type, - struct pid *pid); +void detach_pid(struct pid **pids, struct task_struct *task, enum pid_type= ); +void change_pid(struct pid **pids, struct task_struct *task, enum pid_type, + struct pid *pid); extern void exchange_tids(struct task_struct *task, struct task_struct *ol= d); extern void transfer_pid(struct task_struct *old, struct task_struct *new, enum pid_type); @@ -129,6 +129,7 @@ extern struct pid *find_ge_pid(int nr, struct pid_names= pace *); extern struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid, size_t set_tid_size); extern void free_pid(struct pid *pid); +void free_pids(struct pid **pids); extern void disable_pid_allocation(struct pid_namespace *ns); =20 /* diff --git a/kernel/exit.c b/kernel/exit.c index b5c0cbc6bdfb..0d6df671c8a8 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -122,14 +122,22 @@ static __init int kernel_exit_sysfs_init(void) late_initcall(kernel_exit_sysfs_init); #endif =20 -static void __unhash_process(struct task_struct *p, bool group_dead) +/* + * For things release_task() would like to do *after* tasklist_lock is rel= eased. + */ +struct release_task_post { + struct pid *pids[PIDTYPE_MAX]; +}; + +static void __unhash_process(struct release_task_post *post, struct task_s= truct *p, + bool group_dead) { nr_threads--; - detach_pid(p, PIDTYPE_PID); + detach_pid(post->pids, p, PIDTYPE_PID); if (group_dead) { - detach_pid(p, PIDTYPE_TGID); - detach_pid(p, PIDTYPE_PGID); - detach_pid(p, PIDTYPE_SID); + detach_pid(post->pids, p, PIDTYPE_TGID); + detach_pid(post->pids, p, PIDTYPE_PGID); + detach_pid(post->pids, p, PIDTYPE_SID); =20 list_del_rcu(&p->tasks); list_del_init(&p->sibling); @@ -141,7 +149,7 @@ static void __unhash_process(struct task_struct *p, boo= l group_dead) /* * This function expects the tasklist_lock write-locked. */ -static void __exit_signal(struct task_struct *tsk) +static void __exit_signal(struct release_task_post *post, struct task_stru= ct *tsk) { struct signal_struct *sig =3D tsk->signal; bool group_dead =3D thread_group_leader(tsk); @@ -194,7 +202,7 @@ static void __exit_signal(struct task_struct *tsk) task_io_accounting_add(&sig->ioac, &tsk->ioac); sig->sum_sched_runtime +=3D tsk->se.sum_exec_runtime; sig->nr_threads--; - __unhash_process(tsk, group_dead); + __unhash_process(post, tsk, group_dead); write_sequnlock(&sig->stats_lock); =20 /* @@ -236,10 +244,13 @@ void __weak release_thread(struct task_struct *dead_t= ask) =20 void release_task(struct task_struct *p) { + struct release_task_post post; struct task_struct *leader; struct pid *thread_pid; int zap_leader; repeat: + memset(&post, 0, sizeof(post)); + /* don't need to get the RCU readlock here - the process is dead and * can't be modifying its own credentials. But shut RCU-lockdep up */ rcu_read_lock(); @@ -252,7 +263,7 @@ void release_task(struct task_struct *p) =20 write_lock_irq(&tasklist_lock); ptrace_release_task(p); - __exit_signal(p); + __exit_signal(&post, p); =20 /* * If we are the last non-leader member of the thread diff --git a/kernel/pid.c b/kernel/pid.c index 2ae872f689a7..73625f28c166 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -88,20 +88,6 @@ struct pid_namespace init_pid_ns =3D { }; EXPORT_SYMBOL_GPL(init_pid_ns); =20 -/* - * Note: disable interrupts while the pidmap_lock is held as an - * interrupt might come in and do read_lock(&tasklist_lock). - * - * If we don't disable interrupts there is a nasty deadlock between - * detach_pid()->free_pid() and another cpu that does - * spin_lock(&pidmap_lock) followed by an interrupt routine that does - * read_lock(&tasklist_lock); - * - * After we clean up the tasklist_lock and know there are no - * irq handlers that take it we can leave the interrupts enabled. - * For now it is easier to be safe than to prove it can't happen. - */ - static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); seqcount_spinlock_t pidmap_lock_seq =3D SEQCNT_SPINLOCK_ZERO(pidmap_lock_s= eq, &pidmap_lock); =20 @@ -128,10 +114,11 @@ static void delayed_put_pid(struct rcu_head *rhp) =20 void free_pid(struct pid *pid) { - /* We can be called with write_lock_irq(&tasklist_lock) held */ int i; unsigned long flags; =20 + lockdep_assert_not_held(&tasklist_lock); + spin_lock_irqsave(&pidmap_lock, flags); for (i =3D 0; i <=3D pid->level; i++) { struct upid *upid =3D pid->numbers + i; @@ -160,6 +147,18 @@ void free_pid(struct pid *pid) call_rcu(&pid->rcu, delayed_put_pid); } =20 +void free_pids(struct pid **pids) +{ + int tmp; + + /* + * This can batch pidmap_lock. + */ + for (tmp =3D PIDTYPE_MAX; --tmp >=3D 0; ) + if (pids[tmp]) + free_pid(pids[tmp]); +} + struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid, size_t set_tid_size) { @@ -347,8 +346,8 @@ void attach_pid(struct task_struct *task, enum pid_type= type) hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]); } =20 -static void __change_pid(struct task_struct *task, enum pid_type type, - struct pid *new) +static void __change_pid(struct pid **pids, struct task_struct *task, + enum pid_type type, struct pid *new) { struct pid **pid_ptr, *pid; int tmp; @@ -370,18 +369,19 @@ static void __change_pid(struct task_struct *task, en= um pid_type type, if (pid_has_task(pid, tmp)) return; =20 - free_pid(pid); + WARN_ON(pids[type]); + pids[type] =3D pid; } =20 -void detach_pid(struct task_struct *task, enum pid_type type) +void detach_pid(struct pid **pids, struct task_struct *task, enum pid_type= type) { - __change_pid(task, type, NULL); + __change_pid(pids, task, type, NULL); } =20 -void change_pid(struct task_struct *task, enum pid_type type, +void change_pid(struct pid **pids, struct task_struct *task, enum pid_type= type, struct pid *pid) { - __change_pid(task, type, pid); + __change_pid(pids, task, type, pid); attach_pid(task, type); } =20 diff --git a/kernel/sys.c b/kernel/sys.c index cb366ff8703a..4efca8a97d62 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1085,6 +1085,7 @@ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid) { struct task_struct *p; struct task_struct *group_leader =3D current->group_leader; + struct pid *pids[PIDTYPE_MAX] =3D { 0 }; struct pid *pgrp; int err; =20 @@ -1142,13 +1143,14 @@ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid) goto out; =20 if (task_pgrp(p) !=3D pgrp) - change_pid(p, PIDTYPE_PGID, pgrp); + change_pid(pids, p, PIDTYPE_PGID, pgrp); =20 err =3D 0; out: /* All paths lead to here, thus we are safe. -DaveM */ write_unlock_irq(&tasklist_lock); rcu_read_unlock(); + free_pids(pids); return err; } =20 @@ -1222,21 +1224,22 @@ SYSCALL_DEFINE1(getsid, pid_t, pid) return retval; } =20 -static void set_special_pids(struct pid *pid) +static void set_special_pids(struct pid **pids, struct pid *pid) { struct task_struct *curr =3D current->group_leader; =20 if (task_session(curr) !=3D pid) - change_pid(curr, PIDTYPE_SID, pid); + change_pid(pids, curr, PIDTYPE_SID, pid); =20 if (task_pgrp(curr) !=3D pid) - change_pid(curr, PIDTYPE_PGID, pid); + change_pid(pids, curr, PIDTYPE_PGID, pid); } =20 int ksys_setsid(void) { struct task_struct *group_leader =3D current->group_leader; struct pid *sid =3D task_pid(group_leader); 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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47d06e5sm1167625566b.63.2025.02.05.11.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:33:07 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v4 5/5] pid: drop irq disablement around pidmap_lock Date: Wed, 5 Feb 2025 20:32:21 +0100 Message-ID: <20250205193221.402150-6-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250205193221.402150-1-mjguzik@gmail.com> References: <20250205193221.402150-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" It no longer serves any purpose now that the tasklist_lock -> pidmap_lock ordering got eliminated. Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- kernel/pid.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/kernel/pid.c b/kernel/pid.c index 73625f28c166..900193de4232 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -115,11 +115,10 @@ static void delayed_put_pid(struct rcu_head *rhp) void free_pid(struct pid *pid) { int i; - unsigned long flags; =20 lockdep_assert_not_held(&tasklist_lock); =20 - spin_lock_irqsave(&pidmap_lock, flags); + spin_lock(&pidmap_lock); for (i =3D 0; i <=3D pid->level; i++) { struct upid *upid =3D pid->numbers + i; struct pid_namespace *ns =3D upid->ns; @@ -142,7 +141,7 @@ void free_pid(struct pid *pid) idr_remove(&ns->idr, upid->nr); } pidfs_remove_pid(pid); - spin_unlock_irqrestore(&pidmap_lock, flags); + spin_unlock(&pidmap_lock); =20 call_rcu(&pid->rcu, delayed_put_pid); } @@ -210,7 +209,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *= set_tid, } =20 idr_preload(GFP_KERNEL); - spin_lock_irq(&pidmap_lock); + spin_lock(&pidmap_lock); =20 if (tid) { nr =3D idr_alloc(&tmp->idr, NULL, tid, @@ -237,7 +236,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *= set_tid, nr =3D idr_alloc_cyclic(&tmp->idr, NULL, pid_min, pid_max, GFP_ATOMIC); } - spin_unlock_irq(&pidmap_lock); + spin_unlock(&pidmap_lock); idr_preload_end(); =20 if (nr < 0) { @@ -271,7 +270,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *= set_tid, =20 upid =3D pid->numbers + ns->level; idr_preload(GFP_KERNEL); - spin_lock_irq(&pidmap_lock); + spin_lock(&pidmap_lock); if (!(ns->pid_allocated & PIDNS_ADDING)) goto out_unlock; pidfs_add_pid(pid); @@ -280,18 +279,18 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t= *set_tid, idr_replace(&upid->ns->idr, pid, upid->nr); upid->ns->pid_allocated++; } - spin_unlock_irq(&pidmap_lock); + spin_unlock(&pidmap_lock); idr_preload_end(); =20 return pid; =20 out_unlock: - spin_unlock_irq(&pidmap_lock); + spin_unlock(&pidmap_lock); idr_preload_end(); put_pid_ns(ns); =20 out_free: - spin_lock_irq(&pidmap_lock); + spin_lock(&pidmap_lock); while (++i <=3D ns->level) { upid =3D pid->numbers + i; idr_remove(&upid->ns->idr, upid->nr); @@ -301,7 +300,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *= set_tid, if (ns->pid_allocated =3D=3D PIDNS_ADDING) idr_set_cursor(&ns->idr, 0); =20 - spin_unlock_irq(&pidmap_lock); + spin_unlock(&pidmap_lock); =20 kmem_cache_free(ns->pid_cachep, pid); return ERR_PTR(retval); @@ -309,9 +308,9 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *= set_tid, =20 void disable_pid_allocation(struct pid_namespace *ns) { - spin_lock_irq(&pidmap_lock); + spin_lock(&pidmap_lock); ns->pid_allocated &=3D ~PIDNS_ADDING; - spin_unlock_irq(&pidmap_lock); + spin_unlock(&pidmap_lock); } =20 struct pid *find_pid_ns(int nr, struct pid_namespace *ns) --=20 2.43.0