The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y
git checkout FETCH_HEAD
git cherry-pick -x 690e0ec8e63da9a29b39fedc6ed5da09c7c82651
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '167820540147158(a)kroah.com' --subject-prefix 'PATCH 4.14.y' HEAD^..
Possible dependencies:
690e0ec8e63d ("drm/i915: Don't use stolen memory for ring buffers with LLC")
0d8ee5ba8db4 ("drm/i915: Don't back up pinned LMEM context images and rings during suspend")
c56ce9565374 ("drm/i915 Implement LMEM backup and restore for suspend / resume")
0d9388635a22 ("drm/i915/ttm: Implement a function to copy the contents of two TTM-based objects")
48b096126954 ("drm/i915: Move __i915_gem_free_object to ttm_bo_destroy")
d8ac30fd479c ("drm/i915/ttm: Reorganize the ttm move code somewhat")
32b7cf51a441 ("drm/i915/ttm: Use TTM for system memory")
3c2b8f326e7f ("drm/i915/ttm: Adjust gem flags and caching settings after a move")
0ff375759f64 ("drm/i915: Update object placement flags to be mutable")
b07a6483839a ("drm/i915/ttm: Fix incorrect assumptions about ttm_bo_validate() semantics")
50331a7b5074 ("drm/i915/ttm: accelerated move implementation")
13c2ceb6addb ("drm/i915/ttm: restore min_page_size behaviour")
d53ec322dc7d ("drm/i915/ttm: switch over to ttm_buddy_man")
687c7d0fcf80 ("drm/i915/ttm: remove node usage in our naming")
38f28c0695c0 ("drm/i915/ttm: Calculate the object placement at get_pages time")
c865204e84a1 ("drm/i915/ttm: Fix memory leaks")
cf3e3e86d779 ("drm/i915: Use ttm mmap handling for ttm bo's.")
2e53d7c1147a ("drm/i915/lmem: Verify checks for lmem residency")
213d50927763 ("drm/i915/ttm: Introduce a TTM i915 gem object backend")
2a7005c8a398 ("Merge tag 'drm-intel-gt-next-2021-06-10' of git://anongit.freedesktop.org/drm/drm-intel into drm-next")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 690e0ec8e63da9a29b39fedc6ed5da09c7c82651 Mon Sep 17 00:00:00 2001
From: John Harrison <John.C.Harrison(a)Intel.com>
Date: Wed, 15 Feb 2023 17:11:00 -0800
Subject: [PATCH] drm/i915: Don't use stolen memory for ring buffers with LLC
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Direction from hardware is that stolen memory should never be used for
ring buffer allocations on platforms with LLC. There are too many
caching pitfalls due to the way stolen memory accesses are routed. So
it is safest to just not use it.
Signed-off-by: John Harrison <John.C.Harrison(a)Intel.com>
Fixes: c58b735fc762 ("drm/i915: Allocate rings from stolen")
Cc: Chris Wilson <chris(a)chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen(a)linux.intel.com>
Cc: Jani Nikula <jani.nikula(a)linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi(a)intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin(a)linux.intel.com>
Cc: intel-gfx(a)lists.freedesktop.org
Cc: <stable(a)vger.kernel.org> # v4.9+
Tested-by: Jouni Högander <jouni.hogander(a)intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio(a)intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-2-John…
(cherry picked from commit f54c1f6c697c4297f7ed94283c184acc338a5cf8)
Signed-off-by: Jani Nikula <jani.nikula(a)intel.com>
diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c b/drivers/gpu/drm/i915/gt/intel_ring.c
index 15ec64d881c4..fb1d2595392e 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring.c
@@ -116,7 +116,7 @@ static struct i915_vma *create_ring_vma(struct i915_ggtt *ggtt, int size)
obj = i915_gem_object_create_lmem(i915, size, I915_BO_ALLOC_VOLATILE |
I915_BO_ALLOC_PM_VOLATILE);
- if (IS_ERR(obj) && i915_ggtt_has_aperture(ggtt))
+ if (IS_ERR(obj) && i915_ggtt_has_aperture(ggtt) && !HAS_LLC(i915))
obj = i915_gem_object_create_stolen(i915, size);
if (IS_ERR(obj))
obj = i915_gem_object_create_internal(i915, size);
--
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From: Valentin Schneider <vschneid(a)redhat.com>
commit 05c6257433b7212f07a7e53479a8ab038fc1666a upstream.
Attempting to get a crash dump out of a debug PREEMPT_RT kernel via an NMI
panic() doesn't work. The cause of that lies in the PREEMPT_RT definition
of mutex_trylock():
if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
return 0;
This prevents an nmi_panic() from executing the main body of
__crash_kexec() which does the actual kexec into the kdump kernel. The
warning and return are explained by:
6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softirq context")
[...]
The reasons for this are:
1) There is a potential deadlock in the slowpath
2) Another cpu which blocks on the rtmutex will boost the task
which allegedly locked the rtmutex, but that cannot work
because the hard/softirq context borrows the task context.
Furthermore, grabbing the lock isn't NMI safe, so do away with kexec_mutex
and replace it with an atomic variable. This is somewhat overzealous as
*some* callsites could keep using a mutex (e.g. the sysfs-facing ones
like crash_shrink_memory()), but this has the benefit of involving a
single unified lock and preventing any future NMI-related surprises.
Tested by triggering NMI panics via:
$ echo 1 > /proc/sys/kernel/panic_on_unrecovered_nmi
$ echo 1 > /proc/sys/kernel/unknown_nmi_panic
$ echo 1 > /proc/sys/kernel/panic
$ ipmitool power diag
Link: https://lkml.kernel.org/r/20220630223258.4144112-3-vschneid@redhat.com
Fixes: 6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softirq context")
Signed-off-by: Valentin Schneider <vschneid(a)redhat.com>
Cc: Arnd Bergmann <arnd(a)arndb.de>
Cc: Baoquan He <bhe(a)redhat.com>
Cc: "Eric W . Biederman" <ebiederm(a)xmission.com>
Cc: Juri Lelli <jlelli(a)redhat.com>
Cc: Luis Claudio R. Goncalves <lgoncalv(a)redhat.com>
Cc: Miaohe Lin <linmiaohe(a)huawei.com>
Cc: Petr Mladek <pmladek(a)suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy(a)linutronix.de>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Cc: stable(a)vger.kernel.org # 5.15.x
Signed-off-by: Wen Yang <wenyang.linux(a)foxmail.com>
---
kernel/kexec.c | 11 ++++-------
kernel/kexec_core.c | 20 ++++++++++----------
kernel/kexec_file.c | 4 ++--
kernel/kexec_internal.h | 15 ++++++++++++++-
4 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index b5e40f069768..cb8e6e6f983c 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -93,13 +93,10 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
/*
* Because we write directly to the reserved memory region when loading
- * crash kernels we need a mutex here to prevent multiple crash kernels
- * from attempting to load simultaneously, and to prevent a crash kernel
- * from loading over the top of a in use crash kernel.
- *
- * KISS: always take the mutex.
+ * crash kernels we need a serialization here to prevent multiple crash
+ * kernels from attempting to load simultaneously.
*/
- if (!mutex_trylock(&kexec_mutex))
+ if (!kexec_trylock())
return -EBUSY;
if (flags & KEXEC_ON_CRASH) {
@@ -165,7 +162,7 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
kimage_free(image);
out_unlock:
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
return ret;
}
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index a101d2b77936..bdc2d952911c 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -46,7 +46,7 @@
#include <crypto/hash.h>
#include "kexec_internal.h"
-DEFINE_MUTEX(kexec_mutex);
+atomic_t __kexec_lock = ATOMIC_INIT(0);
/* Per cpu memory for storing cpu states in case of system crash. */
note_buf_t __percpu *crash_notes;
@@ -944,7 +944,7 @@ int kexec_load_disabled;
*/
void __noclone __crash_kexec(struct pt_regs *regs)
{
- /* Take the kexec_mutex here to prevent sys_kexec_load
+ /* Take the kexec_lock here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
* we are using after a panic on a different cpu.
*
@@ -952,7 +952,7 @@ void __noclone __crash_kexec(struct pt_regs *regs)
* of memory the xchg(&kexec_crash_image) would be
* sufficient. But since I reuse the memory...
*/
- if (mutex_trylock(&kexec_mutex)) {
+ if (kexec_trylock()) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
@@ -961,7 +961,7 @@ void __noclone __crash_kexec(struct pt_regs *regs)
machine_crash_shutdown(&fixed_regs);
machine_kexec(kexec_crash_image);
}
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
}
}
STACK_FRAME_NON_STANDARD(__crash_kexec);
@@ -993,13 +993,13 @@ ssize_t crash_get_memory_size(void)
{
ssize_t size = 0;
- if (!mutex_trylock(&kexec_mutex))
+ if (!kexec_trylock())
return -EBUSY;
if (crashk_res.end != crashk_res.start)
size = resource_size(&crashk_res);
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
return size;
}
@@ -1019,7 +1019,7 @@ int crash_shrink_memory(unsigned long new_size)
unsigned long old_size;
struct resource *ram_res;
- if (!mutex_trylock(&kexec_mutex))
+ if (!kexec_trylock())
return -EBUSY;
if (kexec_crash_image) {
@@ -1058,7 +1058,7 @@ int crash_shrink_memory(unsigned long new_size)
insert_resource(&iomem_resource, ram_res);
unlock:
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
return ret;
}
@@ -1130,7 +1130,7 @@ int kernel_kexec(void)
{
int error = 0;
- if (!mutex_trylock(&kexec_mutex))
+ if (!kexec_trylock())
return -EBUSY;
if (!kexec_image) {
error = -EINVAL;
@@ -1206,7 +1206,7 @@ int kernel_kexec(void)
#endif
Unlock:
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
return error;
}
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index f7a4fd4d243f..1fb7ff690577 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -343,7 +343,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
image = NULL;
- if (!mutex_trylock(&kexec_mutex))
+ if (!kexec_trylock())
return -EBUSY;
dest_image = &kexec_image;
@@ -415,7 +415,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
arch_kexec_protect_crashkres();
- mutex_unlock(&kexec_mutex);
+ kexec_unlock();
kimage_free(image);
return ret;
}
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 48aaf2ac0d0d..74da1409cd14 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -13,7 +13,20 @@ void kimage_terminate(struct kimage *image);
int kimage_is_destination_range(struct kimage *image,
unsigned long start, unsigned long end);
-extern struct mutex kexec_mutex;
+/*
+ * Whatever is used to serialize accesses to the kexec_crash_image needs to be
+ * NMI safe, as __crash_kexec() can happen during nmi_panic(), so here we use a
+ * "simple" atomic variable that is acquired with a cmpxchg().
+ */
+extern atomic_t __kexec_lock;
+static inline bool kexec_trylock(void)
+{
+ return atomic_cmpxchg_acquire(&__kexec_lock, 0, 1) == 0;
+}
+static inline void kexec_unlock(void)
+{
+ atomic_set_release(&__kexec_lock, 0);
+}
#ifdef CONFIG_KEXEC_FILE
#include <linux/purgatory.h>
--
2.37.2