Merge branch 'akpm' (patches from Andrew)

Merge still more updates from Andrew Morton:
 "Various trees. Mainly those parts of MM whose linux-next dependents
  are now merged. I'm still sitting on ~160 patches which await merges
  from -next.

  Subsystems affected by this patch series: mm/proc, ipc, dynamic-debug,
  panic, lib, sysctl, mm/gup, mm/pagemap"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (52 commits)
  doc: cgroup: update note about conditions when oom killer is invoked
  module: move the set_fs hack for flush_icache_range to m68k
  nommu: use flush_icache_user_range in brk and mmap
  binfmt_flat: use flush_icache_user_range
  exec: use flush_icache_user_range in read_code
  exec: only build read_code when needed
  m68k: implement flush_icache_user_range
  arm: rename flush_cache_user_range to flush_icache_user_range
  xtensa: implement flush_icache_user_range
  sh: implement flush_icache_user_range
  asm-generic: add a flush_icache_user_range stub
  mm: rename flush_icache_user_range to flush_icache_user_page
  arm,sparc,unicore32: remove flush_icache_user_range
  riscv: use asm-generic/cacheflush.h
  powerpc: use asm-generic/cacheflush.h
  openrisc: use asm-generic/cacheflush.h
  m68knommu: use asm-generic/cacheflush.h
  microblaze: use asm-generic/cacheflush.h
  ia64: use asm-generic/cacheflush.h
  hexagon: use asm-generic/cacheflush.h
  ...

Documentation/admin-guide/cgroup-v2.rst

@@ -1170,6 +1170,13 @@ PAGE_SIZE multiple when read back.
 	Under certain circumstances, the usage may go over the limit
 	temporarily.
 
+	In default configuration regular 0-order allocations always
+	succeed unless OOM killer chooses current task as a victim.
+
+	Some kinds of allocations don't invoke the OOM killer.
+	Caller could retry them differently, return into userspace
+	as -ENOMEM or silently ignore in cases like disk readahead.
+
 	This is the ultimate protection mechanism.  As long as the
 	high limit is used and monitored properly, this limit's
 	utility is limited to providing the final safety net.
@@ -1226,17 +1233,9 @@ PAGE_SIZE multiple when read back.
 		The number of time the cgroup's memory usage was
 		reached the limit and allocation was about to fail.
 
-		Depending on context result could be invocation of OOM
-		killer and retrying allocation or failing allocation.
-
-		Failed allocation in its turn could be returned into
-		userspace as -ENOMEM or silently ignored in cases like
-		disk readahead.  For now OOM in memory cgroup kills
-		tasks iff shortage has happened inside page fault.
-
 		This event is not raised if the OOM killer is not
 		considered as an option, e.g. for failed high-order
-		allocations.
+		allocations or if caller asked to not retry attempts.
 
 	  oom_kill
 		The number of processes belonging to this cgroup

Documentation/admin-guide/dynamic-debug-howto.rst

@@ -13,6 +13,11 @@ kernel code to obtain additional kernel information.  Currently, if
 ``print_hex_dump_debug()``/``print_hex_dump_bytes()`` calls can be dynamically
 enabled per-callsite.
 
+If you do not want to enable dynamic debug globally (i.e. in some embedded
+system), you may set ``CONFIG_DYNAMIC_DEBUG_CORE`` as basic support of dynamic
+debug and add ``ccflags := -DDYNAMIC_DEBUG_MODULE`` into the Makefile of any
+modules which you'd like to dynamically debug later.
+
 If ``CONFIG_DYNAMIC_DEBUG`` is not set, ``print_hex_dump_debug()`` is just
 shortcut for ``print_hex_dump(KERN_DEBUG)``.
 

Documentation/admin-guide/kdump/kdump.rst

@@ -521,6 +521,14 @@ will cause a kdump to occur at the panic() call.  In cases where a user wants
 to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1
 to achieve the same behaviour.
 
+Trigger Kdump on add_taint()
+============================
+
+The kernel parameter panic_on_taint facilitates a conditional call to panic()
+from within add_taint() whenever the value set in this bitmask matches with the
+bit flag being set by add_taint().
+This will cause a kdump to occur at the add_taint()->panic() call.
+
 Contact
 =======
 

Documentation/admin-guide/kernel-parameters.txt

@@ -1445,7 +1445,7 @@
 	hardlockup_all_cpu_backtrace=
 			[KNL] Should the hard-lockup detector generate
 			backtraces on all cpus.
-			Format: <integer>
+			Format: 0 | 1
 
 	hashdist=	[KNL,NUMA] Large hashes allocated during boot
 			are distributed across NUMA nodes.  Defaults on
@@ -1513,9 +1513,9 @@
 
 	hung_task_panic=
 			[KNL] Should the hung task detector generate panics.
-			Format: <integer>
+			Format: 0 | 1
 
-			A nonzero value instructs the kernel to panic when a
+			A value of 1 instructs the kernel to panic when a
 			hung task is detected. The default value is controlled
 			by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
 			option. The value selected by this boot parameter can
@@ -3447,6 +3447,19 @@
 			bit 4: print ftrace buffer
 			bit 5: print all printk messages in buffer
 
+	panic_on_taint=	Bitmask for conditionally calling panic() in add_taint()
+			Format: <hex>[,nousertaint]
+			Hexadecimal bitmask representing the set of TAINT flags
+			that will cause the kernel to panic when add_taint() is
+			called with any of the flags in this set.
+			The optional switch "nousertaint" can be utilized to
+			prevent userspace forced crashes by writing to sysctl
+			/proc/sys/kernel/tainted any flagset matching with the
+			bitmask set on panic_on_taint.
+			See Documentation/admin-guide/tainted-kernels.rst for
+			extra details on the taint flags that users can pick
+			to compose the bitmask to assign to panic_on_taint.
+
 	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
 			on a WARN().
 
@@ -4652,9 +4665,9 @@
 
 	softlockup_panic=
 			[KNL] Should the soft-lockup detector generate panics.
-			Format: <integer>
+			Format: 0 | 1
 
-			A nonzero value instructs the soft-lockup detector
+			A value of 1 instructs the soft-lockup detector
 			to panic the machine when a soft-lockup occurs. It is
 			also controlled by the kernel.softlockup_panic sysctl
 			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
@@ -4663,7 +4676,7 @@
 	softlockup_all_cpu_backtrace=
 			[KNL] Should the soft-lockup detector generate
 			backtraces on all cpus.
-			Format: <integer>
+			Format: 0 | 1
 
 	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
 			See Documentation/admin-guide/laptops/sonypi.rst
@@ -4956,6 +4969,15 @@
 
 	switches=	[HW,M68k]
 
+	sysctl.*=	[KNL]
+			Set a sysctl parameter, right before loading the init
+			process, as if the value was written to the respective
+			/proc/sys/... file. Both '.' and '/' are recognized as
+			separators. Unrecognized parameters and invalid values
+			are reported in the kernel log. Sysctls registered
+			later by a loaded module cannot be set this way.
+			Example: sysctl.vm.swappiness=40
+
 	sysfs.deprecated=0|1 [KNL]
 			Enable/disable old style sysfs layout for old udev
 			on older distributions. When this option is enabled

Documentation/admin-guide/sysctl/kernel.rst

@@ -335,6 +335,20 @@ Path for the hotplug policy agent.
 Default value is "``/sbin/hotplug``".
 
 
+hung_task_all_cpu_backtrace:
+================
+
+If this option is set, the kernel will send an NMI to all CPUs to dump
+their backtraces when a hung task is detected. This file shows up if
+CONFIG_DETECT_HUNG_TASK and CONFIG_SMP are enabled.
+
+0: Won't show all CPUs backtraces when a hung task is detected.
+This is the default behavior.
+
+1: Will non-maskably interrupt all CPUs and dump their backtraces when
+a hung task is detected.
+
+
 hung_task_panic
 ===============
 
@@ -632,6 +646,22 @@ rate for each task.
 scanned for a given scan.
 
 
+oops_all_cpu_backtrace:
+================
+
+If this option is set, the kernel will send an NMI to all CPUs to dump
+their backtraces when an oops event occurs. It should be used as a last
+resort in case a panic cannot be triggered (to protect VMs running, for
+example) or kdump can't be collected. This file shows up if CONFIG_SMP
+is enabled.
+
+0: Won't show all CPUs backtraces when an oops is detected.
+This is the default behavior.
+
+1: Will non-maskably interrupt all CPUs and dump their backtraces when
+an oops event is detected.
+
+
 osrelease, ostype & version
 ===========================
 
@@ -1239,6 +1269,13 @@ ORed together. The letters are seen in "Tainted" line of Oops reports.
 
 See :doc:`/admin-guide/tainted-kernels` for more information.
 
+Note:
+  writes to this sysctl interface will fail with ``EINVAL`` if the kernel is
+  booted with the command line option ``panic_on_taint=<bitmask>,nousertaint``
+  and any of the ORed together values being written to ``tainted`` match with
+  the bitmask declared on panic_on_taint.
+  See :doc:`/admin-guide/kernel-parameters` for more details on that particular
+  kernel command line option and its optional ``nousertaint`` switch.
 
 threads-max
 ===========

Documentation/core-api/pin_user_pages.rst

@@ -148,23 +148,46 @@ NOTE: Some pages, such as DAX pages, cannot be pinned with longterm pins. That's
 because DAX pages do not have a separate page cache, and so "pinning" implies
 locking down file system blocks, which is not (yet) supported in that way.
 
-CASE 3: Hardware with page faulting support
--------------------------------------------
-Here, a well-written driver doesn't normally need to pin pages at all. However,
-if the driver does choose to do so, it can register MMU notifiers for the range,
-and will be called back upon invalidation. Either way (avoiding page pinning, or
-using MMU notifiers to unpin upon request), there is proper synchronization with
-both filesystem and mm (page_mkclean(), munmap(), etc).
-
-Therefore, neither flag needs to be set.
-
-In this case, ideally, neither get_user_pages() nor pin_user_pages() should be
-called. Instead, the software should be written so that it does not pin pages.
-This allows mm and filesystems to operate more efficiently and reliably.
+CASE 3: MMU notifier registration, with or without page faulting hardware
+-------------------------------------------------------------------------
+Device drivers can pin pages via get_user_pages*(), and register for mmu
+notifier callbacks for the memory range. Then, upon receiving a notifier
+"invalidate range" callback , stop the device from using the range, and unpin
+the pages. There may be other possible schemes, such as for example explicitly
+synchronizing against pending IO, that accomplish approximately the same thing.
+
+Or, if the hardware supports replayable page faults, then the device driver can
+avoid pinning entirely (this is ideal), as follows: register for mmu notifier
+callbacks as above, but instead of stopping the device and unpinning in the
+callback, simply remove the range from the device's page tables.
+
+Either way, as long as the driver unpins the pages upon mmu notifier callback,
+then there is proper synchronization with both filesystem and mm
+(page_mkclean(), munmap(), etc). Therefore, neither flag needs to be set.
 
 CASE 4: Pinning for struct page manipulation only
 -------------------------------------------------
-Here, normal GUP calls are sufficient, so neither flag needs to be set.
+If only struct page data (as opposed to the actual memory contents that a page
+is tracking) is affected, then normal GUP calls are sufficient, and neither flag
+needs to be set.
+
+CASE 5: Pinning in order to write to the data within the page
+-------------------------------------------------------------
+Even though neither DMA nor Direct IO is involved, just a simple case of "pin,
+write to a page's data, unpin" can cause a problem. Case 5 may be considered a
+superset of Case 1, plus Case 2, plus anything that invokes that pattern. In
+other words, if the code is neither Case 1 nor Case 2, it may still require
+FOLL_PIN, for patterns like this:
+
+Correct (uses FOLL_PIN calls):
+    pin_user_pages()
+    write to the data within the pages
+    unpin_user_pages()
+
+INCORRECT (uses FOLL_GET calls):
+    get_user_pages()
+    write to the data within the pages
+    put_page()
 
 page_maybe_dma_pinned(): the whole point of pinning
 ===================================================

arch/alpha/include/asm/cacheflush.h

@@ -4,19 +4,6 @@
 
 #include <linux/mm.h>
 
-/* Caches aren't brain-dead on the Alpha. */
-#define flush_cache_all()			do { } while (0)
-#define flush_cache_mm(mm)			do { } while (0)
-#define flush_cache_dup_mm(mm)			do { } while (0)
-#define flush_cache_range(vma, start, end)	do { } while (0)
-#define flush_cache_page(vma, vmaddr, pfn)	do { } while (0)
-#define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0
-#define flush_dcache_page(page)			do { } while (0)
-#define flush_dcache_mmap_lock(mapping)		do { } while (0)
-#define flush_dcache_mmap_unlock(mapping)	do { } while (0)
-#define flush_cache_vmap(start, end)		do { } while (0)
-#define flush_cache_vunmap(start, end)		do { } while (0)
-
 /* Note that the following two definitions are _highly_ dependent
    on the contexts in which they are used in the kernel.  I personally
    think it is criminal how loosely defined these macros are.  */
@@ -48,7 +35,7 @@ extern void smp_imb(void);
 
 extern void __load_new_mm_context(struct mm_struct *);
 static inline void
-flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
+flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
 			unsigned long addr, int len)
 {
 	if (vma->vm_flags & VM_EXEC) {
@@ -59,20 +46,17 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 			mm->context[smp_processor_id()] = 0;
 	}
 }
-#else
-extern void flush_icache_user_range(struct vm_area_struct *vma,
+#define flush_icache_user_page flush_icache_user_page
+#else /* CONFIG_SMP */
+extern void flush_icache_user_page(struct vm_area_struct *vma,
 		struct page *page, unsigned long addr, int len);
-#endif
+#define flush_icache_user_page flush_icache_user_page
+#endif /* CONFIG_SMP */
 
 /* This is used only in __do_fault and do_swap_page.  */
 #define flush_icache_page(vma, page) \
-  flush_icache_user_range((vma), (page), 0, 0)
+	flush_icache_user_page((vma), (page), 0, 0)
 
-#define copy_to_user_page(vma, page, vaddr, dst, src, len) \
-do { memcpy(dst, src, len); \
-     flush_icache_user_range(vma, page, vaddr, len); \
-} while (0)
-#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
-	memcpy(dst, src, len)
+#include <asm-generic/cacheflush.h>
 
 #endif /* _ALPHA_CACHEFLUSH_H */

arch/alpha/kernel/smp.c

@@ -740,7 +740,7 @@ ipi_flush_icache_page(void *x)
 }
 
 void
-flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
+flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
 			unsigned long addr, int len)
 {
 	struct mm_struct *mm = vma->vm_mm;

arch/arm/include/asm/cacheflush.h

@@ -258,11 +258,11 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr
 #define flush_cache_dup_mm(mm) flush_cache_mm(mm)
 
 /*
- * flush_cache_user_range is used when we want to ensure that the
+ * flush_icache_user_range is used when we want to ensure that the
  * Harvard caches are synchronised for the user space address range.
  * This is used for the ARM private sys_cacheflush system call.
  */
-#define flush_cache_user_range(s,e)	__cpuc_coherent_user_range(s,e)
+#define flush_icache_user_range(s,e)	__cpuc_coherent_user_range(s,e)
 
 /*
  * Perform necessary cache operations to ensure that data previously
@@ -318,9 +318,6 @@ extern void flush_kernel_dcache_page(struct page *);
 #define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
 #define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages)
 
-#define flush_icache_user_range(vma,page,addr,len) \
-	flush_dcache_page(page)
-
 /*
  * We don't appear to need to do anything here.  In fact, if we did, we'd
  * duplicate cache flushing elsewhere performed by flush_dcache_page().

arch/arm/kernel/fiq.c

@@ -98,8 +98,8 @@ void set_fiq_handler(void *start, unsigned int length)
 
 	memcpy(base + offset, start, length);
 	if (!cache_is_vipt_nonaliasing())
-		flush_icache_range((unsigned long)base + offset, offset +
-				   length);
+		flush_icache_range((unsigned long)base + offset,
+				   (unsigned long)base + offset + length);
 	flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
 }
 

arch/arm/kernel/traps.c

@@ -566,7 +566,7 @@ __do_cache_op(unsigned long start, unsigned long end)
 		if (fatal_signal_pending(current))
 			return 0;
 
-		ret = flush_cache_user_range(start, start + chunk);
+		ret = flush_icache_user_range(start, start + chunk);
 		if (ret)
 			return ret;