Merge tag 'pidfd-v5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull pidfd updates from Christian Brauner:
 "This patchset makes it possible to retrieve pidfds at process creation
  time by introducing the new flag CLONE_PIDFD to the clone() system
  call. Linus originally suggested to implement this as a new flag to
  clone() instead of making it a separate system call.

  After a thorough review from Oleg CLONE_PIDFD returns pidfds in the
  parent_tidptr argument. This means we can give back the associated pid
  and the pidfd at the same time. Access to process metadata information
  thus becomes rather trivial.

  As has been agreed, CLONE_PIDFD creates file descriptors based on
  anonymous inodes similar to the new mount api. They are made
  unconditional by this patchset as they are now needed by core kernel
  code (vfs, pidfd) even more than they already were before (timerfd,
  signalfd, io_uring, epoll etc.). The core patchset is rather small.
  The bulky looking changelist is caused by David's very simple changes
  to Kconfig to make anon inodes unconditional.

  A pidfd comes with additional information in fdinfo if the kernel
  supports procfs. The fdinfo file contains the pid of the process in
  the callers pid namespace in the same format as the procfs status
  file, i.e. "Pid:\t%d".

  To remove worries about missing metadata access this patchset comes
  with a sample/test program that illustrates how a combination of
  CLONE_PIDFD and pidfd_send_signal() can be used to gain race-free
  access to process metadata through /proc/<pid>.

  Further work based on this patchset has been done by Joel. His work
  makes pidfds pollable. It finished too late for this merge window. I
  would prefer to have it sitting in linux-next for a while and send it
  for inclusion during the 5.3 merge window"

* tag 'pidfd-v5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  samples: show race-free pidfd metadata access
  signal: support CLONE_PIDFD with pidfd_send_signal
  clone: add CLONE_PIDFD
  Make anon_inodes unconditional

7 files changed, 0 insertions, 7 deletions

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 3f5320f46de2..f591026347a5 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -22,7 +22,6 @@ config KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
 	depends on MMU && OF
 	select PREEMPT_NOTIFIERS
-	select ANON_INODES
 	select ARM_GIC
 	select ARM_GIC_V3
 	select ARM_GIC_V3_ITS
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index a3f85624313e..a67121d419a2 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -23,7 +23,6 @@ config KVM
 	depends on OF
 	select MMU_NOTIFIER
 	select PREEMPT_NOTIFIERS
-	select ANON_INODES
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
 	select KVM_MMIO
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index 4528bc9c3cb1..eac25aef21e0 100644
--- a/arch/mips/kvm/Kconfig
+++ b/arch/mips/kvm/Kconfig
@@ -21,7 +21,6 @@ config KVM
 	depends on MIPS_FP_SUPPORT
 	select EXPORT_UASM
 	select PREEMPT_NOTIFIERS
-	select ANON_INODES
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_MMIO
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index bfdde04e4905..f53997a8ca62 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -20,7 +20,6 @@ if VIRTUALIZATION
 config KVM
 	bool
 	select PREEMPT_NOTIFIERS
-	select ANON_INODES
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select SRCU
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 767453faacfc..1816ee48eadd 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -21,7 +21,6 @@ config KVM
 	prompt "Kernel-based Virtual Machine (KVM) support"
 	depends on HAVE_KVM
 	select PREEMPT_NOTIFIERS
-	select ANON_INODES
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select HAVE_KVM_EVENTFD
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0a3cc347143f..e7212731cffb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -44,7 +44,6 @@ config X86
 	#
 	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
-	select ANON_INODES
 	select ARCH_32BIT_OFF_T			if X86_32
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_CLOCKSOURCE_INIT
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 72fa955f4a15..fc042419e670 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -27,7 +27,6 @@ config KVM
 	depends on X86_LOCAL_APIC
 	select PREEMPT_NOTIFIERS
 	select MMU_NOTIFIER
-	select ANON_INODES
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQFD
 	select IRQ_BYPASS_MANAGER