Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 0/8] Use copy_process/create_io_thread in vhost layer
The following patches apply over Linus's, Jens's or mst's trees, but were made over linux-next because patch 6: io_uring: switch to kernel_worker has merge conflicts with Jens Axboe's for-next branch and Paul Moore's selinux tree's next branch. This is V4 of the patchset. It should handle all the review comments posted in V1 - V3. If I missed a comment, please let me know. This patchset allows the vhost layer to do a copy_process on the thread that does the VHOST_SET_OWNER ioctl like how io_uring does a copy_process against its userspace app (Jens, the patches make create_io_thread more generic so that's why you are cc'd). This allows the vhost layer's worker threads to inherit cgroups, namespaces, address space, etc and this worker thread will also be accounted for against that owner/parent process's RLIMIT_NPROC limit. If you are not familiar with qemu and vhost here is more detailed problem description: Qemu will create vhost devices in the kernel which perform network, SCSI, etc IO and management operations from worker threads created by the kthread API. Because the kthread API does a copy_process on the kthreadd thread, the vhost layer has to use kthread_use_mm to access the Qemu thread's memory and cgroup_attach_task_all to add itself to the Qemu thread's cgroups. The problem with this approach is that we then have to add new functions/ args/functionality for every thing we want to inherit. I started doing that here: https://lkml.org/lkml/2021/6/23/1233 for the RLIMIT_NPROC check, but it seems it might be easier to just inherit everything from the beginning, becuase I'd need to do something like that patch several times. For example, the current approach does not support cgroups v2 so commands like virsh emulatorpin do not work. The qemu process can go over its RLIMIT_NPROC. And for future vhost interfaces where we export the vhost thread pid we will want the namespace info. V4: - Drop NO_SIG patch and replaced with Christian's SIG_IGN patch. - Merged Christian's kernel_worker_flags_valid helpers into patch 5 that added the new kernel worker functions. - Fixed extra "i" issue. - Added PF_USER_WORKER flag and added check that kernel_worker_start users had that flag set. Also dropped patches that passed worker flags to copy_thread and replaced with PF_USER_WORKER check. V3: - Add parentheses in p->flag and work_flags check in copy_thread. - Fix check in arm/arm64 which was doing the reverse of other archs where it did likely(!flags) instead of unlikely(flags). V2: - Rename kernel_copy_process to kernel_worker. - Instead of exporting functions, make kernel_worker() a proper function/API that does common work for the caller. - Instead of adding new fields to kernel_clone_args for each option make it flag based similar to CLONE_*. - Drop unused completion struct in vhost. - Fix compile warnings by merging vhost cgroup cleanup patch and vhost conversion patch.
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 1/8] fork: Make IO worker options flag based
This patchset adds a couple new options to kernel_clone_args for IO thread
like/related users. Instead of adding new fields to kernel_clone_args for
each option, this moves us to a flags based approach by first converting
io_thread.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Suggested-by: Christian Brauner <christian.brauner at ubuntu.com>
Acked-by: Christian Brauner <christian.brauner at ubuntu.com>
---
include/linux/sched/task.h | 4 +++-
kernel/fork.c | 4 ++--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index ef02be869cf2..48417c735438 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -18,8 +18,11 @@ struct css_set;
/* All the bits taken by the old clone syscall. */
#define CLONE_LEGACY_FLAGS 0xffffffffULL
+#define KERN_WORKER_IO BIT(0)
+
struct kernel_clone_args {
u64 flags;
+ u32 worker_flags;
int __user *pidfd;
int __user *child_tid;
int __user *parent_tid;
@@ -31,7 +34,6 @@ struct kernel_clone_args {
/* Number of elements in *set_tid */
size_t set_tid_size;
int cgroup;
- int io_thread;
struct cgroup *cgrp;
struct css_set *cset;
};
diff --git a/kernel/fork.c b/kernel/fork.c
index 38681ad44c76..3988106e9609 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2026,7 +2026,7 @@ static __latent_entropy struct task_struct *copy_process(
p = dup_task_struct(current, node);
if (!p)
goto fork_out;
- if (args->io_thread) {
+ if (args->worker_flags & KERN_WORKER_IO) {
/*
* Mark us an IO worker, and block any signal that isn't
* fatal or STOP
@@ -2526,7 +2526,7 @@ struct task_struct *create_io_thread(int (*fn)(void *),
void *arg, int node)
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
.stack = (unsigned long)fn,
.stack_size = (unsigned long)arg,
- .io_thread = 1,
+ .worker_flags = KERN_WORKER_IO,
};
return copy_process(NULL, 0, node, &args);
--
2.25.1
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 2/8] fork: move PF_IO_WORKER's kernel frame setup to new flag
The vhost worker threads need the same frame setup as io_uring's worker
threads, but handle signals differently and do not need the same
scheduling behavior. This patch separate's the frame setup parts of
PF_IO_WORKER into a new PF flag PF_USER_WORKER.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
arch/alpha/kernel/process.c | 2 +-
arch/arc/kernel/process.c | 2 +-
arch/arm/kernel/process.c | 2 +-
arch/arm64/kernel/process.c | 2 +-
arch/csky/kernel/process.c | 2 +-
arch/h8300/kernel/process.c | 2 +-
arch/hexagon/kernel/process.c | 2 +-
arch/ia64/kernel/process.c | 2 +-
arch/m68k/kernel/process.c | 2 +-
arch/microblaze/kernel/process.c | 2 +-
arch/mips/kernel/process.c | 2 +-
arch/nds32/kernel/process.c | 2 +-
arch/nios2/kernel/process.c | 2 +-
arch/openrisc/kernel/process.c | 2 +-
arch/parisc/kernel/process.c | 2 +-
arch/powerpc/kernel/process.c | 2 +-
arch/riscv/kernel/process.c | 2 +-
arch/s390/kernel/process.c | 2 +-
arch/sh/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_64.c | 2 +-
arch/um/kernel/process.c | 2 +-
arch/x86/kernel/process.c | 2 +-
arch/xtensa/kernel/process.c | 2 +-
include/linux/sched.h | 1 +
include/linux/sched/task.h | 1 +
kernel/fork.c | 4 +++-
27 files changed, 29 insertions(+), 25 deletions(-)
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index a5123ea426ce..e350fff2ea14 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -249,7 +249,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index 3793876f42d9..c3f4952cce17 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -191,7 +191,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
childksp[0] = 0; /* fp */
childksp[1] = (unsigned long)ret_from_fork; /* blink */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(c_regs, 0, sizeof(struct pt_regs));
c_callee->r13 = kthread_arg;
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0e2d3051741e..449c9db3942a 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -247,7 +247,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
stack_start,
thread->cpu_domain = get_domain();
#endif
- if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) {
+ if (likely(!(p->flags & (PF_KTHREAD | PF_USER_WORKER)))) {
*childregs = *current_pt_regs();
childregs->ARM_r0 = 0;
if (stack_start)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 40adb8cdbf5a..e2fe88a3ae90 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -333,7 +333,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
stack_start,
ptrauth_thread_init_kernel(p);
- if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) {
+ if (likely(!(p->flags & (PF_KTHREAD | PF_USER_WORKER)))) {
*childregs = *current_pt_regs();
childregs->regs[0] = 0;
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index 3d0ca22cd0e2..509f2bfe4ace 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -49,7 +49,7 @@ int copy_thread(unsigned long clone_flags,
/* setup thread.sp for switch_to !!! */
p->thread.sp = (unsigned long)childstack;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
childstack->r15 = (unsigned long) ret_from_kernel_thread;
childstack->r10 = kthread_arg;
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index 2ac27e4248a4..11baf058b6c5 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
childregs = (struct pt_regs *) (THREAD_SIZE + task_stack_page(p)) - 1;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->retpc = (unsigned long) ret_from_kernel_thread;
childregs->er4 = topstk; /* arg */
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index 6a6835fb4242..f17573b66303 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -73,7 +73,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg,
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
/* r24 <- fn, r25 <- arg */
ss->r24 = usp;
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index e56d63f4abf9..4a58daa56af4 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -338,7 +338,7 @@ copy_thread(unsigned long clone_flags, unsigned long
user_stack_base,
ia64_drop_fpu(p); /* don't pick up stale state from a CPU's fph */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
if (unlikely(!user_stack_base)) {
/* fork_idle() called us */
return 0;
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 1ab692b952cd..e7474a118410 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -157,7 +157,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp, unsigned long arg,
*/
p->thread.fc = USER_DATA;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
memset(frame, 0, sizeof(struct fork_frame));
frame->regs.sr = PS_S;
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 62aa237180b6..5b543be324d4 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -59,7 +59,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg,
struct pt_regs *childregs = task_pt_regs(p);
struct thread_info *ti = task_thread_info(p);
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* if we're creating a new kernel thread then just zeroing all
* the registers. That's OK for a brand new thread.*/
memset(childregs, 0, sizeof(struct pt_regs));
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 95aa86fa6077..d9ca11dd544f 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -120,7 +120,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
/* Put the stack after the struct pt_regs. */
childksp = (unsigned long) childregs;
p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) |
ST0_KERNEL_CUMASK;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
unsigned long status = p->thread.cp0_status;
memset(childregs, 0, sizeof(struct pt_regs));
diff --git a/arch/nds32/kernel/process.c b/arch/nds32/kernel/process.c
index 391895b54d13..2dba51d1889c 100644
--- a/arch/nds32/kernel/process.c
+++ b/arch/nds32/kernel/process.c
@@ -156,7 +156,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
stack_start,
memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
/* kernel thread fn */
p->thread.cpu_context.r6 = stack_start;
diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c
index 9ff37ba2bb60..ce6ad177da15 100644
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -109,7 +109,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp, unsigned long arg,
struct switch_stack *childstack ((struct switch_stack *)childregs) - 1;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index b0698d9ce14f..d1d189c16676 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -172,7 +172,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg,
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *)sp;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(kregs, 0, sizeof(struct pt_regs));
kregs->gpr[20] = usp; /* fn, kernel thread */
kregs->gpr[22] = arg;
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 38ec4ae81239..257bec7e67d4 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -197,7 +197,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
extern void * const ret_from_kernel_thread;
extern void * const child_return;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
memset(cregs, 0, sizeof(struct pt_regs));
if (!usp) /* idle thread */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 50436b52c213..817847723bff 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1700,7 +1700,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
/* Copy registers */
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *) sp;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->gpr[1] = sp + sizeof(struct pt_regs);
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 03ac3aa611f5..8deeb94eb51e 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -125,7 +125,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp, unsigned long arg,
struct pt_regs *childregs = task_pt_regs(p);
/* p->thread holds context to be restored by __switch_to() */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* Kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->gp = gp_in_global;
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 350e94d0cac2..f596843ab55c 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -130,7 +130,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
new_stackp,
frame->sf.gprs[9] = (unsigned long)frame;
/* Store access registers to kernel stack of new process. */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
/* kernel thread */
memset(&frame->childregs, 0, sizeof(struct pt_regs));
frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 717de05c81f4..e74906f53c3e 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -114,7 +114,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp, unsigned long arg,
childregs = task_pt_regs(p);
p->thread.sp = (unsigned long) childregs;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.pc = (unsigned long) ret_from_kernel_thread;
childregs->regs[4] = arg;
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index bbbe0cfef746..978e0bc10ad4 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -296,7 +296,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg,
ti->ksp = (unsigned long) new_stack;
p->thread.kregs = childregs;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
extern int nwindows;
unsigned long psr;
memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index d1cc410d2f64..1c45cd5089f4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -594,7 +594,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg,
sizeof(struct sparc_stackf));
t->fpsaved[0] = 0;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
memset(child_trap_frame, 0, child_stack_sz);
__thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
(current_pt_regs()->tstate + 1) & TSTATE_CWP;
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 457a38db368b..2bc3141cbf01 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -157,7 +157,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct * p, unsigned long tls)
{
void (*handler)(void);
- int kthread = current->flags & (PF_KTHREAD | PF_IO_WORKER);
+ int kthread = current->flags & (PF_KTHREAD | PF_USER_WORKER);
int ret = 0;
p->thread = (struct thread_struct) INIT_THREAD;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 1d9463e3096b..d88be9dd5dfd 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -178,7 +178,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
unsigned long arg,
task_user_gs(p) = get_user_gs(current_pt_regs());
#endif
- if (unlikely(p->flags & PF_IO_WORKER)) {
+ if (unlikely(p->flags & PF_USER_WORKER)) {
/*
* An IO thread is a user space thread, but it doesn't
* return to ret_after_fork().
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 060165340612..61ad0bfbd7ea 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -217,7 +217,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp_thread_fn,
p->thread.sp = (unsigned long)childregs;
- if (!(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (!(p->flags & (PF_KTHREAD | PF_USER_WORKER))) {
struct pt_regs *regs = current_pt_regs();
unsigned long usp = usp_thread_fn ?
usp_thread_fn : regs->areg[1];
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c1a927ddec64..b1027e916be4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1665,6 +1665,7 @@ extern struct pid *cad_pid;
#define PF_VCPU 0x00000001 /* I'm a virtual CPU */
#define PF_IDLE 0x00000002 /* I am an IDLE thread */
#define PF_EXITING 0x00000004 /* Getting shut down */
+#define PF_USER_WORKER 0x00000008 /* Kernel thread cloned from userspace
thread */
#define PF_IO_WORKER 0x00000010 /* Task is an IO worker */
#define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */
#define PF_FORKNOEXEC 0x00000040 /* Forked but didn't exec */
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 48417c735438..53599a99d7e0 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -19,6 +19,7 @@ struct css_set;
#define CLONE_LEGACY_FLAGS 0xffffffffULL
#define KERN_WORKER_IO BIT(0)
+#define KERN_WORKER_USER BIT(1)
struct kernel_clone_args {
u64 flags;
diff --git a/kernel/fork.c b/kernel/fork.c
index 3988106e9609..4f780424de46 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2035,6 +2035,8 @@ static __latent_entropy struct task_struct *copy_process(
siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
}
+ if (args->worker_flags & KERN_WORKER_USER)
+ p->flags |= PF_USER_WORKER;
/*
* This _must_ happen before we call free_task(), i.e. before we jump
* to any of the bad_fork_* labels. This is to avoid freeing
@@ -2526,7 +2528,7 @@ struct task_struct *create_io_thread(int (*fn)(void *),
void *arg, int node)
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
.stack = (unsigned long)fn,
.stack_size = (unsigned long)arg,
- .worker_flags = KERN_WORKER_IO,
+ .worker_flags = KERN_WORKER_IO | KERN_WORKER_USER,
};
return copy_process(NULL, 0, node, &args);
--
2.25.1
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 3/8] fork: add option to not clone or dup files
Each vhost device gets a thread that is used to perform IO and management
operations. Instead of a thread that is accessing a device, the thread is
part of the device, so when it calls the kernel_worker() function added in
the next patch we can't dup or clone the parent's files/FDS because it
would do an extra increment on ourself.
Later, when we do:
Qemu process exits:
do_exit -> exit_files -> put_files_struct -> close_files
we would leak the device's resources because of that extra refcount
on the fd or file_struct.
This patch adds a no_files option so these worker threads can prevent
taking an extra refcount on themselves.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Acked-by: Christian Brauner <christian.brauner at ubuntu.com>
---
include/linux/sched/task.h | 1 +
kernel/fork.c | 11 +++++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 53599a99d7e0..1153f9e5d10e 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -20,6 +20,7 @@ struct css_set;
#define KERN_WORKER_IO BIT(0)
#define KERN_WORKER_USER BIT(1)
+#define KERN_WORKER_NO_FILES BIT(2)
struct kernel_clone_args {
u64 flags;
diff --git a/kernel/fork.c b/kernel/fork.c
index 4f780424de46..3161edac1236 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1532,7 +1532,8 @@ static int copy_fs(unsigned long clone_flags, struct
task_struct *tsk)
return 0;
}
-static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
+static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
+ int no_files)
{
struct files_struct *oldf, *newf;
int error = 0;
@@ -1544,6 +1545,11 @@ static int copy_files(unsigned long clone_flags, struct
task_struct *tsk)
if (!oldf)
goto out;
+ if (no_files) {
+ tsk->files = NULL;
+ goto out;
+ }
+
if (clone_flags & CLONE_FILES) {
atomic_inc(&oldf->count);
goto out;
@@ -2181,7 +2187,8 @@ static __latent_entropy struct task_struct *copy_process(
retval = copy_semundo(clone_flags, p);
if (retval)
goto bad_fork_cleanup_security;
- retval = copy_files(clone_flags, p);
+ retval = copy_files(clone_flags, p,
+ args->worker_flags & KERN_WORKER_NO_FILES);
if (retval)
goto bad_fork_cleanup_semundo;
retval = copy_fs(clone_flags, p);
--
2.25.1
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 4/8] fork: Add KERNEL_WORKER flag to ignore signals
From: Christian Brauner <christian.brauner at ubuntu.com>
Since this is mirroring kthread's sig ignore api introduced in
commit 10ab825bdef8 ("change kernel threads to ignore signals instead of
blocking them")
this patch adds an option flag, KERNEL_WORKER_SIG_IGN, handled in
copy_process() after copy_sighand() and copy_signals() to ease the
transition from kthreads to this new api.
Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
include/linux/sched/task.h | 1 +
kernel/fork.c | 3 +++
2 files changed, 4 insertions(+)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 1153f9e5d10e..5f3928fe0544 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -21,6 +21,7 @@ struct css_set;
#define KERN_WORKER_IO BIT(0)
#define KERN_WORKER_USER BIT(1)
#define KERN_WORKER_NO_FILES BIT(2)
+#define KERN_WORKER_SIG_IGN BIT(3)
struct kernel_clone_args {
u64 flags;
diff --git a/kernel/fork.c b/kernel/fork.c
index 3161edac1236..07f9e410fb64 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2213,6 +2213,9 @@ static __latent_entropy struct task_struct *copy_process(
if (retval)
goto bad_fork_cleanup_io;
+ if (args->worker_flags & KERN_WORKER_SIG_IGN)
+ ignore_signals(p);
+
stackleak_task_init(p);
if (pid != &init_struct_pid) {
--
2.25.1
The vhost layer has similar requirements as io_uring where its worker
threads need to access the userspace thread's memory, want to inherit the
parents's cgroups and namespaces, and be checked against the parent's
RLIMITs. Right now, the vhost layer uses the kthread API which has
kthread_use_mm for mem access, and those threads can use
cgroup_attach_task_all for v1 cgroups, but there are no helpers for the
other items.
This adds a helper to clone a process so we can inherit everything we
want in one call. It's a more generic version of create_io_thread which
will be used by the vhost layer and io_uring in later patches in this set.
[added flag validation code from Christian Brauner's patch]
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Acked-by: Christian Brauner <christian.brauner at ubuntu.com>
---
include/linux/sched/task.h | 4 +++
kernel/fork.c | 71 ++++++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 5f3928fe0544..2bfc0629c868 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -89,6 +89,10 @@ extern void exit_itimers(struct signal_struct *);
extern pid_t kernel_clone(struct kernel_clone_args *kargs);
struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
+struct task_struct *kernel_worker(int (*fn)(void *), void *arg, int node,
+ unsigned long clone_flags, u32 worker_flags);
+__printf(2, 3)
+void kernel_worker_start(struct task_struct *tsk, const char namefmt[], ...);
struct task_struct *fork_idle(int);
struct mm_struct *copy_init_mm(void);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
diff --git a/kernel/fork.c b/kernel/fork.c
index 07f9e410fb64..b04e61a965e2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2544,6 +2544,77 @@ struct task_struct *create_io_thread(int (*fn)(void *),
void *arg, int node)
return copy_process(NULL, 0, node, &args);
}
+static bool kernel_worker_flags_valid(struct kernel_clone_args *kargs)
+{
+ /* Verify that no unknown flags are passed along. */
+ if (kargs->worker_flags & ~(KERN_WORKER_IO | KERN_WORKER_USER |
+ KERN_WORKER_NO_FILES | KERN_WORKER_SIG_IGN))
+ return false;
+
+ /*
+ * If we're ignoring all signals don't allow sharing struct sighand
and
+ * don't bother clearing signal handlers.
+ */
+ if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) &&
+ (kargs->worker_flags & KERN_WORKER_SIG_IGN))
+ return false;
+
+ return true;
+}
+
+/**
+ * kernel_worker - create a copy of a process to be used by the kernel
+ * @fn: thread stack
+ * @arg: data to be passed to fn
+ * @node: numa node to allocate task from
+ * @clone_flags: CLONE flags
+ * @worker_flags: KERN_WORKER flags
+ *
+ * This returns a created task, or an error pointer. The returned task is
+ * inactive, and the caller must fire it up through kernel_worker_start(). If
+ * this is an PF_IO_WORKER all singals but KILL and STOP are blocked.
+ */
+struct task_struct *kernel_worker(int (*fn)(void *), void *arg, int node,
+ unsigned long clone_flags, u32 worker_flags)
+{
+ struct kernel_clone_args args = {
+ .flags = ((lower_32_bits(clone_flags) | CLONE_VM |
+ CLONE_UNTRACED) & ~CSIGNAL),
+ .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
+ .stack = (unsigned long)fn,
+ .stack_size = (unsigned long)arg,
+ .worker_flags = KERN_WORKER_USER | worker_flags,
+ };
+
+ if (!kernel_worker_flags_valid(&args))
+ return ERR_PTR(-EINVAL);
+
+ return copy_process(NULL, 0, node, &args);
+}
+EXPORT_SYMBOL_GPL(kernel_worker);
+
+/**
+ * kernel_worker_start - Start a task created with kernel_worker
+ * @tsk: task to wake up
+ * @namefmt: printf-style format string for the thread name
+ * @arg: arguments for @namefmt
+ */
+void kernel_worker_start(struct task_struct *tsk, const char namefmt[], ...)
+{
+ char name[TASK_COMM_LEN];
+ va_list args;
+
+ WARN_ON(!(tsk->flags & PF_USER_WORKER));
+
+ va_start(args, namefmt);
+ vsnprintf(name, sizeof(name), namefmt, args);
+ set_task_comm(tsk, name);
+ va_end(args);
+
+ wake_up_new_task(tsk);
+}
+EXPORT_SYMBOL_GPL(kernel_worker_start);
+
/*
* Ok, this is the main fork-routine.
*
--
2.25.1
Convert io_uring and io-wq to use kernel_worker.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Reviewed-by: Christian Brauner <christian.brauner at ubuntu.com>
Reviewed-by: Jens Axboe <axboe at kernel.dk>
---
Note: To avoid patch application conflicts this patch was made over
linux-next which has Jens Axboe's block tree's for-next branch and Paul
Moore's selinux tree's next branch because:
commit: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit
support to io_uring")
from Paul's tree had conflicts.
fs/io-wq.c | 15 ++++++++-------
fs/io_uring.c | 11 +++++------
include/linux/sched/task.h | 1 -
3 files changed, 13 insertions(+), 14 deletions(-)
diff --git a/fs/io-wq.c b/fs/io-wq.c
index 962952951126..32b140754496 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -70,6 +70,9 @@ struct io_worker {
#define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
+#define IO_WQ_CLONE_FLAGS (CLONE_FS | CLONE_FILES | CLONE_SIGHAND | \
+ CLONE_THREAD | CLONE_IO)
+
struct io_wqe_acct {
unsigned nr_workers;
unsigned max_workers;
@@ -550,13 +553,9 @@ static int io_wqe_worker(void *data)
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
bool last_timeout = false;
- char buf[TASK_COMM_LEN];
worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
- snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
- set_task_comm(current, buf);
-
audit_alloc_kernel(current);
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
@@ -654,7 +653,7 @@ static void io_init_new_worker(struct io_wqe *wqe, struct
io_worker *worker,
list_add_tail_rcu(&worker->all_list, &wqe->all_list);
worker->flags |= IO_WORKER_F_FREE;
raw_spin_unlock(&wqe->lock);
- wake_up_new_task(tsk);
+ kernel_worker_start(tsk, "iou-wrk-%d", wqe->wq->task->pid);
}
static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
@@ -684,7 +683,8 @@ static void create_worker_cont(struct callback_head *cb)
worker = container_of(cb, struct io_worker, create_work);
clear_bit_unlock(0, &worker->create_state);
wqe = worker->wqe;
- tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+ tsk = kernel_worker(io_wqe_worker, worker, wqe->node,
+ IO_WQ_CLONE_FLAGS, KERN_WORKER_IO);
if (!IS_ERR(tsk)) {
io_init_new_worker(wqe, worker, tsk);
io_worker_release(worker);
@@ -754,7 +754,8 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe
*wqe, int index)
if (index == IO_WQ_ACCT_BOUND)
worker->flags |= IO_WORKER_F_BOUND;
- tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+ tsk = kernel_worker(io_wqe_worker, worker, wqe->node, IO_WQ_CLONE_FLAGS,
+ KERN_WORKER_IO);
if (!IS_ERR(tsk)) {
io_init_new_worker(wqe, worker, tsk);
} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 488aa14da287..5e21ae6d4ff4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7440,12 +7440,8 @@ static int io_sq_thread(void *data)
struct io_sq_data *sqd = data;
struct io_ring_ctx *ctx;
unsigned long timeout = 0;
- char buf[TASK_COMM_LEN];
DEFINE_WAIT(wait);
- snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);
- set_task_comm(current, buf);
-
if (sqd->sq_cpu != -1)
set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
else
@@ -8669,6 +8665,8 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
fdput(f);
}
if (ctx->flags & IORING_SETUP_SQPOLL) {
+ unsigned long flags = CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
+ CLONE_THREAD | CLONE_IO;
struct task_struct *tsk;
struct io_sq_data *sqd;
bool attached;
@@ -8710,7 +8708,8 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
sqd->task_pid = current->pid;
sqd->task_tgid = current->tgid;
- tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
+ tsk = kernel_worker(io_sq_thread, sqd, NUMA_NO_NODE,
+ flags, KERN_WORKER_IO);
if (IS_ERR(tsk)) {
ret = PTR_ERR(tsk);
goto err_sqpoll;
@@ -8718,7 +8717,7 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
sqd->thread = tsk;
ret = io_uring_alloc_task_context(tsk, ctx);
- wake_up_new_task(tsk);
+ kernel_worker_start(tsk, "iou-sqp-%d", sqd->task_pid);
if (ret)
goto err;
} else if (p->flags & IORING_SETUP_SQ_AFF) {
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 2bfc0629c868..c8ab90e28f11 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -88,7 +88,6 @@ extern void exit_files(struct task_struct *);
extern void exit_itimers(struct signal_struct *);
extern pid_t kernel_clone(struct kernel_clone_args *kargs);
-struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
struct task_struct *kernel_worker(int (*fn)(void *), void *arg, int node,
unsigned long clone_flags, u32 worker_flags);
__printf(2, 3)
--
2.25.1
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 7/8] vhost: move worker thread fields to new struct
This is just a prep patch. It moves the worker related fields to a new
vhost_worker struct and moves the code around to create some helpers that
will be used in the next patches.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha at redhat.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
---
drivers/vhost/vhost.c | 98 ++++++++++++++++++++++++++++---------------
drivers/vhost/vhost.h | 11 +++--
2 files changed, 72 insertions(+), 37 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 59edb5a1ffe2..c9a1f706989c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -263,8 +263,8 @@ void vhost_work_queue(struct vhost_dev *dev, struct
vhost_work *work)
* sure it was not in the list.
* test_and_set_bit() implies a memory barrier.
*/
- llist_add(&work->node, &dev->work_list);
- wake_up_process(dev->worker);
+ llist_add(&work->node, &dev->worker->work_list);
+ wake_up_process(dev->worker->task);
}
}
EXPORT_SYMBOL_GPL(vhost_work_queue);
@@ -272,7 +272,7 @@ EXPORT_SYMBOL_GPL(vhost_work_queue);
/* A lockless hint for busy polling code to exit the loop */
bool vhost_has_work(struct vhost_dev *dev)
{
- return !llist_empty(&dev->work_list);
+ return dev->worker &&
!llist_empty(&dev->worker->work_list);
}
EXPORT_SYMBOL_GPL(vhost_has_work);
@@ -343,7 +343,8 @@ static void vhost_vq_reset(struct vhost_dev *dev,
static int vhost_worker(void *data)
{
- struct vhost_dev *dev = data;
+ struct vhost_worker *worker = data;
+ struct vhost_dev *dev = worker->dev;
struct vhost_work *work, *work_next;
struct llist_node *node;
@@ -358,7 +359,7 @@ static int vhost_worker(void *data)
break;
}
- node = llist_del_all(&dev->work_list);
+ node = llist_del_all(&worker->work_list);
if (!node)
schedule();
@@ -368,7 +369,7 @@ static int vhost_worker(void *data)
llist_for_each_entry_safe(work, work_next, node, node) {
clear_bit(VHOST_WORK_QUEUED, &work->flags);
__set_current_state(TASK_RUNNING);
- kcov_remote_start_common(dev->kcov_handle);
+ kcov_remote_start_common(worker->kcov_handle);
work->fn(work);
kcov_remote_stop();
if (need_resched())
@@ -487,7 +488,6 @@ void vhost_dev_init(struct vhost_dev *dev,
dev->byte_weight = byte_weight;
dev->use_worker = use_worker;
dev->msg_handler = msg_handler;
- init_llist_head(&dev->work_list);
init_waitqueue_head(&dev->wait);
INIT_LIST_HEAD(&dev->read_list);
INIT_LIST_HEAD(&dev->pending_list);
@@ -579,10 +579,60 @@ static void vhost_detach_mm(struct vhost_dev *dev)
dev->mm = NULL;
}
+static void vhost_worker_free(struct vhost_dev *dev)
+{
+ struct vhost_worker *worker = dev->worker;
+
+ if (!worker)
+ return;
+
+ dev->worker = NULL;
+ WARN_ON(!llist_empty(&worker->work_list));
+ kthread_stop(worker->task);
+ kfree(worker);
+}
+
+static int vhost_worker_create(struct vhost_dev *dev)
+{
+ struct vhost_worker *worker;
+ struct task_struct *task;
+ int ret;
+
+ worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
+ if (!worker)
+ return -ENOMEM;
+
+ dev->worker = worker;
+ worker->dev = dev;
+ worker->kcov_handle = kcov_common_handle();
+ init_llist_head(&worker->work_list);
+
+ task = kthread_create(vhost_worker, worker, "vhost-%d",
current->pid);
+ if (IS_ERR(task)) {
+ ret = PTR_ERR(task);
+ goto free_worker;
+ }
+
+ worker->task = task;
+ wake_up_process(task); /* avoid contributing to loadavg */
+
+ ret = vhost_attach_cgroups(dev);
+ if (ret)
+ goto stop_worker;
+
+ return 0;
+
+stop_worker:
+ kthread_stop(worker->task);
+free_worker:
+ kfree(worker);
+ dev->worker = NULL;
+ return ret;
+}
+
/* Caller should have device mutex */
long vhost_dev_set_owner(struct vhost_dev *dev)
{
- struct task_struct *worker;
int err;
/* Is there an owner already? */
@@ -593,36 +643,21 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
vhost_attach_mm(dev);
- dev->kcov_handle = kcov_common_handle();
if (dev->use_worker) {
- worker = kthread_create(vhost_worker, dev,
- "vhost-%d", current->pid);
- if (IS_ERR(worker)) {
- err = PTR_ERR(worker);
- goto err_worker;
- }
-
- dev->worker = worker;
- wake_up_process(worker); /* avoid contributing to loadavg */
-
- err = vhost_attach_cgroups(dev);
+ err = vhost_worker_create(dev);
if (err)
- goto err_cgroup;
+ goto err_worker;
}
err = vhost_dev_alloc_iovecs(dev);
if (err)
- goto err_cgroup;
+ goto err_iovecs;
return 0;
-err_cgroup:
- if (dev->worker) {
- kthread_stop(dev->worker);
- dev->worker = NULL;
- }
+err_iovecs:
+ vhost_worker_free(dev);
err_worker:
vhost_detach_mm(dev);
- dev->kcov_handle = 0;
err_mm:
return err;
}
@@ -712,12 +747,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
- WARN_ON(!llist_empty(&dev->work_list));
- if (dev->worker) {
- kthread_stop(dev->worker);
- dev->worker = NULL;
- dev->kcov_handle = 0;
- }
+ vhost_worker_free(dev);
vhost_detach_mm(dev);
}
EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 638bb640d6b4..102ce25e4e13 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,6 +25,13 @@ struct vhost_work {
unsigned long flags;
};
+struct vhost_worker {
+ struct task_struct *task;
+ struct llist_head work_list;
+ struct vhost_dev *dev;
+ u64 kcov_handle;
+};
+
/* Poll a file (eventfd or socket) */
/* Note: there's nothing vhost specific about this structure. */
struct vhost_poll {
@@ -148,8 +155,7 @@ struct vhost_dev {
struct vhost_virtqueue **vqs;
int nvqs;
struct eventfd_ctx *log_ctx;
- struct llist_head work_list;
- struct task_struct *worker;
+ struct vhost_worker *worker;
struct vhost_iotlb *umem;
struct vhost_iotlb *iotlb;
spinlock_t iotlb_lock;
@@ -159,7 +165,6 @@ struct vhost_dev {
int iov_limit;
int weight;
int byte_weight;
- u64 kcov_handle;
bool use_worker;
int (*msg_handler)(struct vhost_dev *dev,
struct vhost_iotlb_msg *msg);
--
2.25.1
Mike Christie
2021-Oct-07 21:44 UTC
[PATCH V4 8/8] vhost: use kernel_worker to check RLIMITs and inherit v2 cgroups
For vhost workers we use the kthread API which inherit's its values from
and checks against the kthreadd thread. This results in cgroups v2 not
working and the wrong RLIMITs being checked. This patch has us use the
kernel_copy_process function which will inherit its values/checks from the
thread that owns the device.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
---
drivers/vhost/vhost.c | 65 +++++++++++++++----------------------------
drivers/vhost/vhost.h | 7 ++++-
2 files changed, 28 insertions(+), 44 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index c9a1f706989c..9aa04fcdf210 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -22,7 +22,6 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/kthread.h>
-#include <linux/cgroup.h>
#include <linux/module.h>
#include <linux/sort.h>
#include <linux/sched/mm.h>
@@ -344,17 +343,14 @@ static void vhost_vq_reset(struct vhost_dev *dev,
static int vhost_worker(void *data)
{
struct vhost_worker *worker = data;
- struct vhost_dev *dev = worker->dev;
struct vhost_work *work, *work_next;
struct llist_node *node;
- kthread_use_mm(dev->mm);
-
for (;;) {
/* mb paired w/ kthread_stop */
set_current_state(TASK_INTERRUPTIBLE);
- if (kthread_should_stop()) {
+ if (test_bit(VHOST_WORKER_FLAG_STOP, &worker->flags)) {
__set_current_state(TASK_RUNNING);
break;
}
@@ -376,8 +372,9 @@ static int vhost_worker(void *data)
schedule();
}
}
- kthread_unuse_mm(dev->mm);
- return 0;
+
+ complete(worker->exit_done);
+ do_exit(0);
}
static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
@@ -517,31 +514,6 @@ long vhost_dev_check_owner(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
-struct vhost_attach_cgroups_struct {
- struct vhost_work work;
- struct task_struct *owner;
- int ret;
-};
-
-static void vhost_attach_cgroups_work(struct vhost_work *work)
-{
- struct vhost_attach_cgroups_struct *s;
-
- s = container_of(work, struct vhost_attach_cgroups_struct, work);
- s->ret = cgroup_attach_task_all(s->owner, current);
-}
-
-static int vhost_attach_cgroups(struct vhost_dev *dev)
-{
- struct vhost_attach_cgroups_struct attach;
-
- attach.owner = current;
- vhost_work_init(&attach.work, vhost_attach_cgroups_work);
- vhost_work_queue(dev, &attach.work);
- vhost_work_dev_flush(dev);
- return attach.ret;
-}
-
/* Caller should have device mutex */
bool vhost_dev_has_owner(struct vhost_dev *dev)
{
@@ -579,6 +551,16 @@ static void vhost_detach_mm(struct vhost_dev *dev)
dev->mm = NULL;
}
+static void vhost_worker_stop(struct vhost_worker *worker)
+{
+ DECLARE_COMPLETION_ONSTACK(exit_done);
+
+ worker->exit_done = &exit_done;
+ set_bit(VHOST_WORKER_FLAG_STOP, &worker->flags);
+ wake_up_process(worker->task);
+ wait_for_completion(worker->exit_done);
+}
+
static void vhost_worker_free(struct vhost_dev *dev)
{
struct vhost_worker *worker = dev->worker;
@@ -588,7 +570,7 @@ static void vhost_worker_free(struct vhost_dev *dev)
dev->worker = NULL;
WARN_ON(!llist_empty(&worker->work_list));
- kthread_stop(worker->task);
+ vhost_worker_stop(worker);
kfree(worker);
}
@@ -603,27 +585,24 @@ static int vhost_worker_create(struct vhost_dev *dev)
return -ENOMEM;
dev->worker = worker;
- worker->dev = dev;
worker->kcov_handle = kcov_common_handle();
init_llist_head(&worker->work_list);
- task = kthread_create(vhost_worker, worker, "vhost-%d",
current->pid);
+ /*
+ * vhost used to use the kthread API which ignores all signals by
+ * default and the drivers expect this behavior.
+ */
+ task = kernel_worker(vhost_worker, worker, NUMA_NO_NODE, CLONE_FS,
+ KERN_WORKER_NO_FILES | KERN_WORKER_SIG_IGN);
if (IS_ERR(task)) {
ret = PTR_ERR(task);
goto free_worker;
}
worker->task = task;
- wake_up_process(task); /* avoid contributing to loadavg */
-
- ret = vhost_attach_cgroups(dev);
- if (ret)
- goto stop_worker;
-
+ kernel_worker_start(task, "vhost-%d", current->pid);
return 0;
-stop_worker:
- kthread_stop(worker->task);
free_worker:
kfree(worker);
dev->worker = NULL;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 102ce25e4e13..09748694cb66 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,11 +25,16 @@ struct vhost_work {
unsigned long flags;
};
+enum {
+ VHOST_WORKER_FLAG_STOP,
+};
+
struct vhost_worker {
struct task_struct *task;
+ struct completion *exit_done;
struct llist_head work_list;
- struct vhost_dev *dev;
u64 kcov_handle;
+ unsigned long flags;
};
/* Poll a file (eventfd or socket) */
--
2.25.1