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fa7d9493 |
| 21-Nov-2018 |
Babu Moger <Babu.Moger@amd.com> |
x86/resctrl: Rename and move rdt files to a separate directory
New generation of AMD processors add support for RDT (or QOS) features. Together, these features will be called RESCTRL. With more than
x86/resctrl: Rename and move rdt files to a separate directory
New generation of AMD processors add support for RDT (or QOS) features. Together, these features will be called RESCTRL. With more than one vendors supporting these features, it seems more appropriate to rename these files.
Create a new directory with the name 'resctrl' and move all the intel_rdt files to the new directory. This way all the resctrl related code resides inside one directory.
[ bp: Add SPDX identifier to the Makefile ]
Suggested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Babu Moger <babu.moger@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: "Chang S. Bae" <chang.seok.bae@intel.com> Cc: David Miller <davem@davemloft.net> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Dmitry Safonov <dima@arista.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <linux-doc@vger.kernel.org> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Pu Wen <puwen@hygon.cn> Cc: <qianyue.zj@alibaba-inc.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Reinette Chatre <reinette.chatre@intel.com> Cc: Rian Hunter <rian@alum.mit.edu> Cc: Sherry Hurwitz <sherry.hurwitz@amd.com> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Lendacky <Thomas.Lendacky@amd.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: <xiaochen.shen@intel.com> Link: https://lkml.kernel.org/r/20181121202811.4492-2-babu.moger@amd.com
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#
397e352c |
| 17-Dec-2020 |
Fenghua Yu <fenghua.yu@intel.com> |
x86/resctrl: Don't move a task to the same resource group commit a0195f314a25582b38993bf30db11c300f4f4611 upstream. Shakeel Butt reported in [1] that a user can request a task to be
x86/resctrl: Don't move a task to the same resource group commit a0195f314a25582b38993bf30db11c300f4f4611 upstream. Shakeel Butt reported in [1] that a user can request a task to be moved to a resource group even if the task is already in the group. It just wastes time to do the move operation which could be costly to send IPI to a different CPU. Add a sanity check to ensure that the move operation only happens when the task is not already in the resource group. [1] https://lore.kernel.org/lkml/CALvZod7E9zzHwenzf7objzGKsdBmVwTgEJ0nPgs0LUFU3SN5Pw@mail.gmail.com/ Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files") Reported-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/962ede65d8e95be793cb61102cca37f7bb018e66.1608243147.git.reinette.chatre@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
34e4ae4d |
| 17-Dec-2020 |
Fenghua Yu <fenghua.yu@intel.com> |
x86/resctrl: Use an IPI instead of task_work_add() to update PQR_ASSOC MSR commit ae28d1aae48a1258bd09a6f707ebb4231d79a761 upstream. Currently, when moving a task to a resource grou
x86/resctrl: Use an IPI instead of task_work_add() to update PQR_ASSOC MSR commit ae28d1aae48a1258bd09a6f707ebb4231d79a761 upstream. Currently, when moving a task to a resource group the PQR_ASSOC MSR is updated with the new closid and rmid in an added task callback. If the task is running, the work is run as soon as possible. If the task is not running, the work is executed later in the kernel exit path when the kernel returns to the task again. Updating the PQR_ASSOC MSR as soon as possible on the CPU a moved task is running is the right thing to do. Queueing work for a task that is not running is unnecessary (the PQR_ASSOC MSR is already updated when the task is scheduled in) and causing system resource waste with the way in which it is implemented: Work to update the PQR_ASSOC register is queued every time the user writes a task id to the "tasks" file, even if the task already belongs to the resource group. This could result in multiple pending work items associated with a single task even if they are all identical and even though only a single update with most recent values is needed. Specifically, even if a task is moved between different resource groups while it is sleeping then it is only the last move that is relevant but yet a work item is queued during each move. This unnecessary queueing of work items could result in significant system resource waste, especially on tasks sleeping for a long time. For example, as demonstrated by Shakeel Butt in [1] writing the same task id to the "tasks" file can quickly consume significant memory. The same problem (wasted system resources) occurs when moving a task between different resource groups. As pointed out by Valentin Schneider in [2] there is an additional issue with the way in which the queueing of work is done in that the task_struct update is currently done after the work is queued, resulting in a race with the register update possibly done before the data needed by the update is available. To solve these issues, update the PQR_ASSOC MSR in a synchronous way right after the new closid and rmid are ready during the task movement, only if the task is running. If a moved task is not running nothing is done since the PQR_ASSOC MSR will be updated next time the task is scheduled. This is the same way used to update the register when tasks are moved as part of resource group removal. [1] https://lore.kernel.org/lkml/CALvZod7E9zzHwenzf7objzGKsdBmVwTgEJ0nPgs0LUFU3SN5Pw@mail.gmail.com/ [2] https://lore.kernel.org/lkml/20201123022433.17905-1-valentin.schneider@arm.com [ bp: Massage commit message and drop the two update_task_closid_rmid() variants. ] Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files") Reported-by: Shakeel Butt <shakeelb@google.com> Reported-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: James Morse <james.morse@arm.com> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/17aa2fb38fc12ce7bb710106b3e7c7b45acb9e94.1608243147.git.reinette.chatre@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
fae3a13d |
| 30-Nov-2020 |
Babu Moger <babu.moger@amd.com> |
x86/resctrl: Fix AMD L3 QOS CDP enable/disable When the AMD QoS feature CDP (code and data prioritization) is enabled or disabled, the CDP bit in MSR 0000_0C81 is written on one of the C
x86/resctrl: Fix AMD L3 QOS CDP enable/disable When the AMD QoS feature CDP (code and data prioritization) is enabled or disabled, the CDP bit in MSR 0000_0C81 is written on one of the CPUs in an L3 domain (core complex). That is not correct - the CDP bit needs to be updated on all the logical CPUs in the domain. This was not spelled out clearly in the spec earlier. The specification has been updated and the updated document, "AMD64 Technology Platform Quality of Service Extensions Publication # 56375 Revision: 1.02 Issue Date: October 2020" is available now. Refer the section: Code and Data Prioritization. Fix the issue by adding a new flag arch_has_per_cpu_cfg in rdt_cache data structure. The documentation can be obtained at: https://developer.amd.com/wp-content/resources/56375.pdf Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 [ bp: Massage commit message. ] Fixes: 4d05bf71f157 ("x86/resctrl: Introduce AMD QOS feature") Signed-off-by: Babu Moger <babu.moger@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Link: https://lkml.kernel.org/r/160675180380.15628.3309402017215002347.stgit@bmoger-ubuntu
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#
75899924 |
| 30-Oct-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Add necessary kernfs_put() calls to prevent refcount leak On resource group creation via a mkdir an extra kernfs_node reference is obtained by kernfs_get() to ensure that th
x86/resctrl: Add necessary kernfs_put() calls to prevent refcount leak On resource group creation via a mkdir an extra kernfs_node reference is obtained by kernfs_get() to ensure that the rdtgroup structure remains accessible for the rdtgroup_kn_unlock() calls where it is removed on deletion. Currently the extra kernfs_node reference count is only dropped by kernfs_put() in rdtgroup_kn_unlock() while the rdtgroup structure is removed in a few other locations that lack the matching reference drop. In call paths of rmdir and umount, when a control group is removed, kernfs_remove() is called to remove the whole kernfs nodes tree of the control group (including the kernfs nodes trees of all child monitoring groups), and then rdtgroup structure is freed by kfree(). The rdtgroup structures of all child monitoring groups under the control group are freed by kfree() in free_all_child_rdtgrp(). Before calling kfree() to free the rdtgroup structures, the kernfs node of the control group itself as well as the kernfs nodes of all child monitoring groups still take the extra references which will never be dropped to 0 and the kernfs nodes will never be freed. It leads to reference count leak and kernfs_node_cache memory leak. For example, reference count leak is observed in these two cases: (1) mount -t resctrl resctrl /sys/fs/resctrl mkdir /sys/fs/resctrl/c1 mkdir /sys/fs/resctrl/c1/mon_groups/m1 umount /sys/fs/resctrl (2) mkdir /sys/fs/resctrl/c1 mkdir /sys/fs/resctrl/c1/mon_groups/m1 rmdir /sys/fs/resctrl/c1 The same reference count leak issue also exists in the error exit paths of mkdir in mkdir_rdt_prepare() and rdtgroup_mkdir_ctrl_mon(). Fix this issue by following changes to make sure the extra kernfs_node reference on rdtgroup is dropped before freeing the rdtgroup structure. (1) Introduce rdtgroup removal helper rdtgroup_remove() to wrap up kernfs_put() and kfree(). (2) Call rdtgroup_remove() in rdtgroup removal path where the rdtgroup structure is about to be freed by kfree(). (3) Call rdtgroup_remove() or kernfs_put() as appropriate in the error exit paths of mkdir where an extra reference is taken by kernfs_get(). Fixes: f3cbeacaa06e ("x86/intel_rdt/cqm: Add rmdir support") Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files") Fixes: 60cf5e101fd4 ("x86/intel_rdt: Add mkdir to resctrl file system") Reported-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1604085088-31707-1-git-send-email-xiaochen.shen@intel.com
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#
fd8d9db3 |
| 30-Oct-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Remove superfluous kernfs_get() calls to prevent refcount leak Willem reported growing of kernfs_node_cache entries in slabtop when repeatedly creating and removing resctrl
x86/resctrl: Remove superfluous kernfs_get() calls to prevent refcount leak Willem reported growing of kernfs_node_cache entries in slabtop when repeatedly creating and removing resctrl subdirectories as well as when repeatedly mounting and unmounting the resctrl filesystem. On resource group (control as well as monitoring) creation via a mkdir an extra kernfs_node reference is obtained to ensure that the rdtgroup structure remains accessible for the rdtgroup_kn_unlock() calls where it is removed on deletion. The kernfs_node reference count is dropped by kernfs_put() in rdtgroup_kn_unlock(). With the above explaining the need for one kernfs_get()/kernfs_put() pair in resctrl there are more places where a kernfs_node reference is obtained without a corresponding release. The excessive amount of reference count on kernfs nodes will never be dropped to 0 and the kernfs nodes will never be freed in the call paths of rmdir and umount. It leads to reference count leak and kernfs_node_cache memory leak. Remove the superfluous kernfs_get() calls and expand the existing comments surrounding the remaining kernfs_get()/kernfs_put() pair that remains in use. Superfluous kernfs_get() calls are removed from two areas: (1) In call paths of mount and mkdir, when kernfs nodes for "info", "mon_groups" and "mon_data" directories and sub-directories are created, the reference count of newly created kernfs node is set to 1. But after kernfs_create_dir() returns, superfluous kernfs_get() are called to take an additional reference. (2) kernfs_get() calls in rmdir call paths. Fixes: 17eafd076291 ("x86/intel_rdt: Split resource group removal in two") Fixes: 4af4a88e0c92 ("x86/intel_rdt/cqm: Add mount,umount support") Fixes: f3cbeacaa06e ("x86/intel_rdt/cqm: Add rmdir support") Fixes: d89b7379015f ("x86/intel_rdt/cqm: Add mon_data") Fixes: c7d9aac61311 ("x86/intel_rdt/cqm: Add mkdir support for RDT monitoring") Fixes: 5dc1d5c6bac2 ("x86/intel_rdt: Simplify info and base file lists") Fixes: 60cf5e101fd4 ("x86/intel_rdt: Add mkdir to resctrl file system") Fixes: 4e978d06dedb ("x86/intel_rdt: Add "info" files to resctrl file system") Reported-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Tested-by: Willem de Bruijn <willemb@google.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1604085053-31639-1-git-send-email-xiaochen.shen@intel.com
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Revision tags: v5.8.17, v5.8.16 |
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#
91989c70 |
| 16-Oct-2020 |
Jens Axboe <axboe@kernel.dk> |
task_work: cleanup notification modes A previous commit changed the notification mode from true/false to an int, allowing notify-no, notify-yes, or signal-notify. This was backwards
task_work: cleanup notification modes A previous commit changed the notification mode from true/false to an int, allowing notify-no, notify-yes, or signal-notify. This was backwards compatible in the sense that any existing true/false user would translate to either 0 (on notification sent) or 1, the latter which mapped to TWA_RESUME. TWA_SIGNAL was assigned a value of 2. Clean this up properly, and define a proper enum for the notification mode. Now we have: - TWA_NONE. This is 0, same as before the original change, meaning no notification requested. - TWA_RESUME. This is 1, same as before the original change, meaning that we use TIF_NOTIFY_RESUME. - TWA_SIGNAL. This uses TIF_SIGPENDING/JOBCTL_TASK_WORK for the notification. Clean up all the callers, switching their 0/1/false/true to using the appropriate TWA_* mode for notifications. Fixes: e91b48162332 ("task_work: teach task_work_add() to do signal_wake_up()") Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Revision tags: v5.8.15, v5.9, v5.8.14, v5.8.13, v5.8.12, v5.8.11, v5.8.10, v5.8.9, v5.8.8, v5.8.7, v5.8.6, v5.4.62, v5.8.5, v5.8.4, v5.4.61 |
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#
29b6bd41 |
| 24-Aug-2020 |
Fenghua Yu <fenghua.yu@intel.com> |
x86/resctrl: Enable user to view thread or core throttling mode Early Intel hardware implementations of Memory Bandwidth Allocation (MBA) could only control bandwidth at the processor co
x86/resctrl: Enable user to view thread or core throttling mode Early Intel hardware implementations of Memory Bandwidth Allocation (MBA) could only control bandwidth at the processor core level. This meant that when two processes with different bandwidth allocations ran simultaneously on the same core the hardware had to resolve this difference. It did so by applying the higher throttling value (lower bandwidth) to both processes. Newer implementations can apply different throttling values to each thread on a core. Introduce a new resctrl file, "thread_throttle_mode", on Intel systems that shows to the user how throttling values are allocated, per-core or per-thread. On systems that support per-core throttling, the file will display "max". On newer systems that support per-thread throttling, the file will display "per-thread". AMD confirmed in [1] that AMD bandwidth allocation is already at thread level but that the AMD implementation does not use a memory delay throttle mode. So to avoid confusion the thread throttling mode would be UNDEFINED on AMD systems and the "thread_throttle_mode" file will not be visible. Originally-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Link: https://lkml.kernel.org/r/1598296281-127595-3-git-send-email-fenghua.yu@intel.com Link: [1] https://lore.kernel.org/lkml/18d277fd-6523-319c-d560-66b63ff606b8@amd.com
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Revision tags: v5.8.3, v5.4.60, v5.8.2, v5.4.59, v5.8.1, v5.4.58, v5.4.57, v5.4.56, v5.8, v5.7.12, v5.4.55, v5.7.11, v5.4.54, v5.7.10, v5.4.53, v5.4.52, v5.7.9, v5.7.8, v5.4.51 |
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e6b2fac3 |
| 08-Jul-2020 |
James Morse <james.morse@arm.com> |
x86/resctrl: Use is_closid_match() in more places rdtgroup_tasks_assigned() and show_rdt_tasks() loop over threads testing for a CTRL/MON group match by closid/rmid with the provided rdt
x86/resctrl: Use is_closid_match() in more places rdtgroup_tasks_assigned() and show_rdt_tasks() loop over threads testing for a CTRL/MON group match by closid/rmid with the provided rdtgrp. Further down the file are helpers to do this, move these further up and make use of them here. These helpers additionally check for alloc/mon capable. This is harmless as rdtgroup_mkdir() tests these capable flags before allowing the config directories to be created. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Link: https://lkml.kernel.org/r/20200708163929.2783-7-james.morse@arm.com
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ae0fbedd |
| 08-Jul-2020 |
James Morse <james.morse@arm.com> |
x86/resctrl: Fix stale comment The comment in rdtgroup_init() refers to the non existent function rdt_mount(), which has now been renamed rdt_get_tree(). Fix the comment. Si
x86/resctrl: Fix stale comment The comment in rdtgroup_init() refers to the non existent function rdt_mount(), which has now been renamed rdt_get_tree(). Fix the comment. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Link: https://lkml.kernel.org/r/20200708163929.2783-4-james.morse@arm.com
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Revision tags: v5.4.50, v5.7.7, v5.4.49, v5.7.6, v5.7.5, v5.4.48, v5.7.4, v5.7.3, v5.4.47, v5.4.46, v5.7.2, v5.4.45, v5.7.1, v5.4.44 |
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#
cc5277fe |
| 02-Jun-2020 |
Dan Carpenter <dan.carpenter@oracle.com> |
x86/resctrl: Fix a NULL vs IS_ERR() static checker warning in rdt_cdp_peer_get() The callers don't expect *d_cdp to be set to an error pointer, they only check for NULL. This leads to a
x86/resctrl: Fix a NULL vs IS_ERR() static checker warning in rdt_cdp_peer_get() The callers don't expect *d_cdp to be set to an error pointer, they only check for NULL. This leads to a static checker warning: arch/x86/kernel/cpu/resctrl/rdtgroup.c:2648 __init_one_rdt_domain() warn: 'd_cdp' could be an error pointer This would not trigger a bug in this specific case because __init_one_rdt_domain() calls it with a valid domain that would not have a negative id and thus not trigger the return of the ERR_PTR(). If this was a negative domain id then the call to rdt_find_domain() in domain_add_cpu() would have returned the ERR_PTR() much earlier and the creation of the domain with an invalid id would have been prevented. Even though a bug is not triggered currently the right and safe thing to do is to set the pointer to NULL because that is what can be checked for when the caller is handling the CDP and non-CDP cases. Fixes: 52eb74339a62 ("x86/resctrl: Fix rdt_find_domain() return value and checks") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Reinette Chatre <reinette.chatre@intel.com> Acked-by: Fenghua Yu <fenghua.yu@intel.com> Link: https://lkml.kernel.org/r/20200602193611.GA190851@mwanda
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#
c1e8d7c6 |
| 08-Jun-2020 |
Michel Lespinasse <walken@google.com> |
mmap locking API: convert mmap_sem comments Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [ak
mmap locking API: convert mmap_sem comments Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revision tags: v5.7, v5.4.43, v5.4.42, v5.4.41, v5.4.40, v5.4.39 |
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#
46637d45 |
| 05-May-2020 |
Reinette Chatre <reinette.chatre@intel.com> |
x86/resctrl: Maintain MBM counter width per resource The original Memory Bandwidth Monitoring (MBM) architectural definition defines counters of up to 62 bits in the IA32_QM_CTR MSR,
x86/resctrl: Maintain MBM counter width per resource The original Memory Bandwidth Monitoring (MBM) architectural definition defines counters of up to 62 bits in the IA32_QM_CTR MSR, and the first-generation MBM implementation uses 24 bit counters. Software is required to poll at 1 second or faster to ensure that data is retrieved before a counter rollover occurs more than once under worst conditions. As system bandwidths scale the software requirement is maintained with the introduction of a per-resource enumerable MBM counter width. In preparation for supporting hardware with an enumerable MBM counter width the current globally static MBM counter width is moved to a per-resource MBM counter width. Currently initialized to 24 always to result in no functional change. In essence there is one function, mbm_overflow_count() that needs to know the counter width to handle rollovers. The static value used within mbm_overflow_count() will be replaced with a value discovered from the hardware. Support for learning the MBM counter width from hardware is added in the change that follows. Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/e36743b9800f16ce600f86b89127391f61261f23.1588715690.git.reinette.chatre@intel.com
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#
8dd97c65 |
| 05-May-2020 |
Reinette Chatre <reinette.chatre@intel.com> |
x86/resctrl: Rename asm/resctrl_sched.h to asm/resctrl.h asm/resctrl_sched.h is dedicated to the code used for configuration of the CPU resource control state when a task is scheduled.
x86/resctrl: Rename asm/resctrl_sched.h to asm/resctrl.h asm/resctrl_sched.h is dedicated to the code used for configuration of the CPU resource control state when a task is scheduled. Rename resctrl_sched.h to resctrl.h in preparation of additions that will no longer make this file dedicated to work done during scheduling. No functional change. Suggested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/6914e0ef880b539a82a6d889f9423496d471ad1d.1588715690.git.reinette.chatre@intel.com
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Revision tags: v5.4.38, v5.4.37, v5.4.36, v5.4.35, v5.4.34, v5.4.33, v5.4.32, v5.4.31, v5.4.30, v5.4.29, v5.6, v5.4.28, v5.4.27, v5.4.26, v5.4.25, v5.4.24, v5.4.23, v5.4.22 |
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9fe04507 |
| 21-Feb-2020 |
James Morse <james.morse@arm.com> |
x86/resctrl: Preserve CDP enable over CPU hotplug Resctrl assumes that all CPUs are online when the filesystem is mounted, and that CPUs remember their CDP-enabled state over CPU hotplug
x86/resctrl: Preserve CDP enable over CPU hotplug Resctrl assumes that all CPUs are online when the filesystem is mounted, and that CPUs remember their CDP-enabled state over CPU hotplug. This goes wrong when resctrl's CDP-enabled state changes while all the CPUs in a domain are offline. When a domain comes online, enable (or disable!) CDP to match resctrl's current setting. Fixes: 5ff193fbde20 ("x86/intel_rdt: Add basic resctrl filesystem support") Suggested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20200221162105.154163-1-james.morse@arm.com
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b0151da5 |
| 17-Mar-2020 |
Reinette Chatre <reinette.chatre@intel.com> |
x86/resctrl: Fix invalid attempt at removing the default resource group The default resource group ("rdtgroup_default") is associated with the root of the resctrl filesystem and should n
x86/resctrl: Fix invalid attempt at removing the default resource group The default resource group ("rdtgroup_default") is associated with the root of the resctrl filesystem and should never be removed. New resource groups can be created as subdirectories of the resctrl filesystem and they can be removed from user space. There exists a safeguard in the directory removal code (rdtgroup_rmdir()) that ensures that only subdirectories can be removed by testing that the directory to be removed has to be a child of the root directory. A possible deadlock was recently fixed with 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference"). This fix involved associating the private data of the "mon_groups" and "mon_data" directories to the resource group to which they belong instead of NULL as before. A consequence of this change was that the original safeguard code preventing removal of "mon_groups" and "mon_data" found in the root directory failed resulting in attempts to remove the default resource group that ends in a BUG: kernel BUG at mm/slub.c:3969! invalid opcode: 0000 [#1] SMP PTI Call Trace: rdtgroup_rmdir+0x16b/0x2c0 kernfs_iop_rmdir+0x5c/0x90 vfs_rmdir+0x7a/0x160 do_rmdir+0x17d/0x1e0 do_syscall_64+0x55/0x1d0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by improving the directory removal safeguard to ensure that subdirectories of the resctrl root directory can only be removed if they are a child of the resctrl filesystem's root _and_ not associated with the default resource group. Fixes: 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference") Reported-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/884cbe1773496b5dbec1b6bd11bb50cffa83603d.1584461853.git.reinette.chatre@intel.com
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c9d35ee0 |
| 08-Feb-2020 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs file system parameter updates from Al Viro: "Saner fs_parser.c guts and data struc
Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs file system parameter updates from Al Viro: "Saner fs_parser.c guts and data structures. The system-wide registry of syntax types (string/enum/int32/oct32/.../etc.) is gone and so is the horror switch() in fs_parse() that would have to grow another case every time something got added to that system-wide registry. New syntax types can be added by filesystems easily now, and their namespace is that of functions - not of system-wide enum members. IOW, they can be shared or kept private and if some turn out to be widely useful, we can make them common library helpers, etc., without having to do anything whatsoever to fs_parse() itself. And we already get that kind of requests - the thing that finally pushed me into doing that was "oh, and let's add one for timeouts - things like 15s or 2h". If some filesystem really wants that, let them do it. Without somebody having to play gatekeeper for the variants blessed by direct support in fs_parse(), TYVM. Quite a bit of boilerplate is gone. And IMO the data structures make a lot more sense now. -200LoC, while we are at it" * 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (25 commits) tmpfs: switch to use of invalfc() cgroup1: switch to use of errorfc() et.al. procfs: switch to use of invalfc() hugetlbfs: switch to use of invalfc() cramfs: switch to use of errofc() et.al. gfs2: switch to use of errorfc() et.al. fuse: switch to use errorfc() et.al. ceph: use errorfc() and friends instead of spelling the prefix out prefix-handling analogues of errorf() and friends turn fs_param_is_... into functions fs_parse: handle optional arguments sanely fs_parse: fold fs_parameter_desc/fs_parameter_spec fs_parser: remove fs_parameter_description name field add prefix to fs_context->log ceph_parse_param(), ceph_parse_mon_ips(): switch to passing fc_log new primitive: __fs_parse() switch rbd and libceph to p_log-based primitives struct p_log, variants of warnf() et.al. taking that one instead teach logfc() to handle prefices, give it saner calling conventions get rid of cg_invalf() ...
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Revision tags: v5.4.21, v5.4.20, v5.4.19, v5.4.18, v5.4.17, v5.4.16, v5.5, v5.4.15, v5.4.14, v5.4.13, v5.4.12, v5.4.11, v5.4.10, v5.4.9, v5.4.8, v5.4.7, v5.4.6, v5.4.5, v5.4.4, v5.4.3, v5.3.15, v5.4.2, v5.4.1, v5.3.14, v5.4, v5.3.13, v5.3.12, v5.3.11, v5.3.10, v5.3.9, v5.3.8, v5.3.7, v5.3.6, v5.3.5, v5.3.4, v5.3.3, v5.3.2, v5.3.1, v5.3, v5.2.14, v5.3-rc8 |
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d7167b14 |
| 07-Sep-2019 |
Al Viro <viro@zeniv.linux.org.uk> |
fs_parse: fold fs_parameter_desc/fs_parameter_spec The former contains nothing but a pointer to an array of the latter... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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96cafb9c |
| 06-Dec-2019 |
Eric Sandeen <sandeen@sandeen.net> |
fs_parser: remove fs_parameter_description name field Unused now. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-b
fs_parser: remove fs_parameter_description name field Unused now. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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b70a2d6b |
| 31-Jan-2020 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: "Misc fixes: - three fixes and a cleanup for th
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: "Misc fixes: - three fixes and a cleanup for the resctrl code - a HyperV fix - a fix to /proc/kcore contents in live debugging sessions - a fix for the x86 decoder opcode map" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/decoder: Add TEST opcode to Group3-2 x86/resctrl: Clean up unused function parameter in mkdir path x86/resctrl: Fix a deadlock due to inaccurate reference x86/resctrl: Fix use-after-free due to inaccurate refcount of rdtgroup x86/resctrl: Fix use-after-free when deleting resource groups x86/hyper-v: Add "polling" bit to hv_synic_sint x86/crash: Define arch_crash_save_vmcoreinfo() if CONFIG_CRASH_CORE=y
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4244057c |
| 28-Jan-2020 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 resource control updates from Ingo Molnar: "The main change in this tree is the exte
Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 resource control updates from Ingo Molnar: "The main change in this tree is the extension of the resctrl procfs ABI with a new file that helps tooling to navigate from tasks back to resctrl groups: /proc/{pid}/cpu_resctrl_groups. Also fix static key usage for certain feature combinations and simplify the task exit resctrl case" * 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/resctrl: Add task resctrl information display x86/resctrl: Check monitoring static key in the MBM overflow handler x86/resctrl: Do not reconfigure exiting tasks
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32ada3b9 |
| 08-Jan-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Clean up unused function parameter in mkdir path Commit 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference") changed the argument to rdtg
x86/resctrl: Clean up unused function parameter in mkdir path Commit 334b0f4e9b1b ("x86/resctrl: Fix a deadlock due to inaccurate reference") changed the argument to rdtgroup_kn_lock_live()/rdtgroup_kn_unlock() within mkdir_rdt_prepare(). That change resulted in an unused function parameter to mkdir_rdt_prepare(). Clean up the unused function parameter in mkdir_rdt_prepare() and its callers rdtgroup_mkdir_mon() and rdtgroup_mkdir_ctrl_mon(). Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1578500886-21771-5-git-send-email-xiaochen.shen@intel.com
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#
334b0f4e |
| 08-Jan-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Fix a deadlock due to inaccurate reference There is a race condition which results in a deadlock when rmdir and mkdir execute concurrently: $ ls /sys/fs/resctrl/c1/
x86/resctrl: Fix a deadlock due to inaccurate reference There is a race condition which results in a deadlock when rmdir and mkdir execute concurrently: $ ls /sys/fs/resctrl/c1/mon_groups/m1/ cpus cpus_list mon_data tasks Thread 1: rmdir /sys/fs/resctrl/c1 Thread 2: mkdir /sys/fs/resctrl/c1/mon_groups/m1 3 locks held by mkdir/48649: #0: (sb_writers#17){.+.+}, at: [<ffffffffb4ca2aa0>] mnt_want_write+0x20/0x50 #1: (&type->i_mutex_dir_key#8/1){+.+.}, at: [<ffffffffb4c8c13b>] filename_create+0x7b/0x170 #2: (rdtgroup_mutex){+.+.}, at: [<ffffffffb4a4389d>] rdtgroup_kn_lock_live+0x3d/0x70 4 locks held by rmdir/48652: #0: (sb_writers#17){.+.+}, at: [<ffffffffb4ca2aa0>] mnt_want_write+0x20/0x50 #1: (&type->i_mutex_dir_key#8/1){+.+.}, at: [<ffffffffb4c8c3cf>] do_rmdir+0x13f/0x1e0 #2: (&type->i_mutex_dir_key#8){++++}, at: [<ffffffffb4c86d5d>] vfs_rmdir+0x4d/0x120 #3: (rdtgroup_mutex){+.+.}, at: [<ffffffffb4a4389d>] rdtgroup_kn_lock_live+0x3d/0x70 Thread 1 is deleting control group "c1". Holding rdtgroup_mutex, kernfs_remove() removes all kernfs nodes under directory "c1" recursively, then waits for sub kernfs node "mon_groups" to drop active reference. Thread 2 is trying to create a subdirectory "m1" in the "mon_groups" directory. The wrapper kernfs_iop_mkdir() takes an active reference to the "mon_groups" directory but the code drops the active reference to the parent directory "c1" instead. As a result, Thread 1 is blocked on waiting for active reference to drop and never release rdtgroup_mutex, while Thread 2 is also blocked on trying to get rdtgroup_mutex. Thread 1 (rdtgroup_rmdir) Thread 2 (rdtgroup_mkdir) (rmdir /sys/fs/resctrl/c1) (mkdir /sys/fs/resctrl/c1/mon_groups/m1) ------------------------- ------------------------- kernfs_iop_mkdir /* * kn: "m1", parent_kn: "mon_groups", * prgrp_kn: parent_kn->parent: "c1", * * "mon_groups", parent_kn->active++: 1 */ kernfs_get_active(parent_kn) kernfs_iop_rmdir /* "c1", kn->active++ */ kernfs_get_active(kn) rdtgroup_kn_lock_live atomic_inc(&rdtgrp->waitcount) /* "c1", kn->active-- */ kernfs_break_active_protection(kn) mutex_lock rdtgroup_rmdir_ctrl free_all_child_rdtgrp sentry->flags = RDT_DELETED rdtgroup_ctrl_remove rdtgrp->flags = RDT_DELETED kernfs_get(kn) kernfs_remove(rdtgrp->kn) __kernfs_remove /* "mon_groups", sub_kn */ atomic_add(KN_DEACTIVATED_BIAS, &sub_kn->active) kernfs_drain(sub_kn) /* * sub_kn->active == KN_DEACTIVATED_BIAS + 1, * waiting on sub_kn->active to drop, but it * never drops in Thread 2 which is blocked * on getting rdtgroup_mutex. */ Thread 1 hangs here ----> wait_event(sub_kn->active == KN_DEACTIVATED_BIAS) ... rdtgroup_mkdir rdtgroup_mkdir_mon(parent_kn, prgrp_kn) mkdir_rdt_prepare(parent_kn, prgrp_kn) rdtgroup_kn_lock_live(prgrp_kn) atomic_inc(&rdtgrp->waitcount) /* * "c1", prgrp_kn->active-- * * The active reference on "c1" is * dropped, but not matching the * actual active reference taken * on "mon_groups", thus causing * Thread 1 to wait forever while * holding rdtgroup_mutex. */ kernfs_break_active_protection( prgrp_kn) /* * Trying to get rdtgroup_mutex * which is held by Thread 1. */ Thread 2 hangs here ----> mutex_lock ... The problem is that the creation of a subdirectory in the "mon_groups" directory incorrectly releases the active protection of its parent directory instead of itself before it starts waiting for rdtgroup_mutex. This is triggered by the rdtgroup_mkdir() flow calling rdtgroup_kn_lock_live()/rdtgroup_kn_unlock() with kernfs node of the parent control group ("c1") as argument. It should be called with kernfs node "mon_groups" instead. What is currently missing is that the kn->priv of "mon_groups" is NULL instead of pointing to the rdtgrp. Fix it by pointing kn->priv to rdtgrp when "mon_groups" is created. Then it could be passed to rdtgroup_kn_lock_live()/rdtgroup_kn_unlock() instead. And then it operates on the same rdtgroup structure but handles the active reference of kernfs node "mon_groups" to prevent deadlock. The same changes are also made to the "mon_data" directories. This results in some unused function parameters that will be cleaned up in follow-up patch as the focus here is on the fix only in support of backporting efforts. Fixes: c7d9aac61311 ("x86/intel_rdt/cqm: Add mkdir support for RDT monitoring") Suggested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1578500886-21771-4-git-send-email-xiaochen.shen@intel.com
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#
074fadee |
| 08-Jan-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Fix use-after-free due to inaccurate refcount of rdtgroup There is a race condition in the following scenario which results in an use-after-free issue when reading a monitor
x86/resctrl: Fix use-after-free due to inaccurate refcount of rdtgroup There is a race condition in the following scenario which results in an use-after-free issue when reading a monitoring file and deleting the parent ctrl_mon group concurrently: Thread 1 calls atomic_inc() to take refcount of rdtgrp and then calls kernfs_break_active_protection() to drop the active reference of kernfs node in rdtgroup_kn_lock_live(). In Thread 2, kernfs_remove() is a blocking routine. It waits on all sub kernfs nodes to drop the active reference when removing all subtree kernfs nodes recursively. Thread 2 could block on kernfs_remove() until Thread 1 calls kernfs_break_active_protection(). Only after kernfs_remove() completes the refcount of rdtgrp could be trusted. Before Thread 1 calls atomic_inc() and kernfs_break_active_protection(), Thread 2 could call kfree() when the refcount of rdtgrp (sentry) is 0 instead of 1 due to the race. In Thread 1, in rdtgroup_kn_unlock(), referring to earlier rdtgrp memory (rdtgrp->waitcount) which was already freed in Thread 2 results in use-after-free issue. Thread 1 (rdtgroup_mondata_show) Thread 2 (rdtgroup_rmdir) -------------------------------- ------------------------- rdtgroup_kn_lock_live /* * kn active protection until * kernfs_break_active_protection(kn) */ rdtgrp = kernfs_to_rdtgroup(kn) rdtgroup_kn_lock_live atomic_inc(&rdtgrp->waitcount) mutex_lock rdtgroup_rmdir_ctrl free_all_child_rdtgrp /* * sentry->waitcount should be 1 * but is 0 now due to the race. */ kfree(sentry)*[1] /* * Only after kernfs_remove() * completes, the refcount of * rdtgrp could be trusted. */ atomic_inc(&rdtgrp->waitcount) /* kn->active-- */ kernfs_break_active_protection(kn) rdtgroup_ctrl_remove rdtgrp->flags = RDT_DELETED /* * Blocking routine, wait for * all sub kernfs nodes to drop * active reference in * kernfs_break_active_protection. */ kernfs_remove(rdtgrp->kn) rdtgroup_kn_unlock mutex_unlock atomic_dec_and_test( &rdtgrp->waitcount) && (flags & RDT_DELETED) kernfs_unbreak_active_protection(kn) kfree(rdtgrp) mutex_lock mon_event_read rdtgroup_kn_unlock mutex_unlock /* * Use-after-free: refer to earlier rdtgrp * memory which was freed in [1]. */ atomic_dec_and_test(&rdtgrp->waitcount) && (flags & RDT_DELETED) /* kn->active++ */ kernfs_unbreak_active_protection(kn) kfree(rdtgrp) Fix it by moving free_all_child_rdtgrp() to after kernfs_remove() in rdtgroup_rmdir_ctrl() to ensure it has the accurate refcount of rdtgrp. Fixes: f3cbeacaa06e ("x86/intel_rdt/cqm: Add rmdir support") Suggested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1578500886-21771-3-git-send-email-xiaochen.shen@intel.com
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#
b8511ccc |
| 08-Jan-2020 |
Xiaochen Shen <xiaochen.shen@intel.com> |
x86/resctrl: Fix use-after-free when deleting resource groups A resource group (rdtgrp) contains a reference count (rdtgrp->waitcount) that indicates how many waiters expect this rdtgrp
x86/resctrl: Fix use-after-free when deleting resource groups A resource group (rdtgrp) contains a reference count (rdtgrp->waitcount) that indicates how many waiters expect this rdtgrp to exist. Waiters could be waiting on rdtgroup_mutex or some work sitting on a task's workqueue for when the task returns from kernel mode or exits. The deletion of a rdtgrp is intended to have two phases: (1) while holding rdtgroup_mutex the necessary cleanup is done and rdtgrp->flags is set to RDT_DELETED, (2) after releasing the rdtgroup_mutex, the rdtgrp structure is freed only if there are no waiters and its flag is set to RDT_DELETED. Upon gaining access to rdtgroup_mutex or rdtgrp, a waiter is required to check for the RDT_DELETED flag. When unmounting the resctrl file system or deleting ctrl_mon groups, all of the subdirectories are removed and the data structure of rdtgrp is forcibly freed without checking rdtgrp->waitcount. If at this point there was a waiter on rdtgrp then a use-after-free issue occurs when the waiter starts running and accesses the rdtgrp structure it was waiting on. See kfree() calls in [1], [2] and [3] in these two call paths in following scenarios: (1) rdt_kill_sb() -> rmdir_all_sub() -> free_all_child_rdtgrp() (2) rdtgroup_rmdir() -> rdtgroup_rmdir_ctrl() -> free_all_child_rdtgrp() There are several scenarios that result in use-after-free issue in following: Scenario 1: ----------- In Thread 1, rdtgroup_tasks_write() adds a task_work callback move_myself(). If move_myself() is scheduled to execute after Thread 2 rdt_kill_sb() is finished, referring to earlier rdtgrp memory (rdtgrp->waitcount) which was already freed in Thread 2 results in use-after-free issue. Thread 1 (rdtgroup_tasks_write) Thread 2 (rdt_kill_sb) ------------------------------- ---------------------- rdtgroup_kn_lock_live atomic_inc(&rdtgrp->waitcount) mutex_lock rdtgroup_move_task __rdtgroup_move_task /* * Take an extra refcount, so rdtgrp cannot be freed * before the call back move_myself has been invoked */ atomic_inc(&rdtgrp->waitcount) /* Callback move_myself will be scheduled for later */ task_work_add(move_myself) rdtgroup_kn_unlock mutex_unlock atomic_dec_and_test(&rdtgrp->waitcount) && (flags & RDT_DELETED) mutex_lock rmdir_all_sub /* * sentry and rdtgrp are freed * without checking refcount */ free_all_child_rdtgrp kfree(sentry)*[1] kfree(rdtgrp)*[2] mutex_unlock /* * Callback is scheduled to execute * after rdt_kill_sb is finished */ move_myself /* * Use-after-free: refer to earlier rdtgrp * memory which was freed in [1] or [2]. */ atomic_dec_and_test(&rdtgrp->waitcount) && (flags & RDT_DELETED) kfree(rdtgrp) Scenario 2: ----------- In Thread 1, rdtgroup_tasks_write() adds a task_work callback move_myself(). If move_myself() is scheduled to execute after Thread 2 rdtgroup_rmdir() is finished, referring to earlier rdtgrp memory (rdtgrp->waitcount) which was already freed in Thread 2 results in use-after-free issue. Thread 1 (rdtgroup_tasks_write) Thread 2 (rdtgroup_rmdir) ------------------------------- ------------------------- rdtgroup_kn_lock_live atomic_inc(&rdtgrp->waitcount) mutex_lock rdtgroup_move_task __rdtgroup_move_task /* * Take an extra refcount, so rdtgrp cannot be freed * before the call back move_myself has been invoked */ atomic_inc(&rdtgrp->waitcount) /* Callback move_myself will be scheduled for later */ task_work_add(move_myself) rdtgroup_kn_unlock mutex_unlock atomic_dec_and_test(&rdtgrp->waitcount) && (flags & RDT_DELETED) rdtgroup_kn_lock_live atomic_inc(&rdtgrp->waitcount) mutex_lock rdtgroup_rmdir_ctrl free_all_child_rdtgrp /* * sentry is freed without * checking refcount */ kfree(sentry)*[3] rdtgroup_ctrl_remove rdtgrp->flags = RDT_DELETED rdtgroup_kn_unlock mutex_unlock atomic_dec_and_test( &rdtgrp->waitcount) && (flags & RDT_DELETED) kfree(rdtgrp) /* * Callback is scheduled to execute * after rdt_kill_sb is finished */ move_myself /* * Use-after-free: refer to earlier rdtgrp * memory which was freed in [3]. */ atomic_dec_and_test(&rdtgrp->waitcount) && (flags & RDT_DELETED) kfree(rdtgrp) If CONFIG_DEBUG_SLAB=y, Slab corruption on kmalloc-2k can be observed like following. Note that "0x6b" is POISON_FREE after kfree(). The corrupted bits "0x6a", "0x64" at offset 0x424 correspond to waitcount member of struct rdtgroup which was freed: Slab corruption (Not tainted): kmalloc-2k start=ffff9504c5b0d000, len=2048 420: 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkjkkkkkkkkkkk Single bit error detected. Probably bad RAM. Run memtest86+ or a similar memory test tool. Next obj: start=ffff9504c5b0d800, len=2048 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Slab corruption (Not tainted): kmalloc-2k start=ffff9504c58ab800, len=2048 420: 6b 6b 6b 6b 64 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkdkkkkkkkkkkk Prev obj: start=ffff9504c58ab000, len=2048 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Fix this by taking reference count (waitcount) of rdtgrp into account in the two call paths that currently do not do so. Instead of always freeing the resource group it will only be freed if there are no waiters on it. If there are waiters, the resource group will have its flags set to RDT_DELETED. It will be left to the waiter to free the resource group when it starts running and finding that it was the last waiter and the resource group has been removed (rdtgrp->flags & RDT_DELETED) since. (1) rdt_kill_sb() -> rmdir_all_sub() -> free_all_child_rdtgrp() (2) rdtgroup_rmdir() -> rdtgroup_rmdir_ctrl() -> free_all_child_rdtgrp() Fixes: f3cbeacaa06e ("x86/intel_rdt/cqm: Add rmdir support") Fixes: 60cf5e101fd4 ("x86/intel_rdt: Add mkdir to resctrl file system") Suggested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1578500886-21771-2-git-send-email-xiaochen.shen@intel.com
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