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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, boris.ostrovsky@oracle.com,
	chris@chris-wilson.co.uk, hch@lst.de,
	jani.nikula@linux.intel.com, jgross@suse.com,
	joonas.lahtinen@linux.intel.com, linux-mm@kvack.org,
	matthew.auld@intel.com, minchan@kernel.org,
	mm-commits@vger.kernel.org, ngupta@vflare.org,
	peterz@infradead.org, rodrigo.vivi@intel.com,
	sstabellini@kernel.org, torvalds@linux-foundation.org,
	tvrtko.ursulin@linux.intel.com, urezki@gmail.com,
	willy@infradead.org
Subject: [patch 27/40] mm: update the documentation for vfree
Date: Sat, 17 Oct 2020 16:15:03 -0700
Message-ID: <20201017231503.Mq52Vrou6%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201017161314.88890b87fae7446ccc13c902@linux-foundation.org>

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: update the documentation for vfree

Patch series "remove alloc_vm_area", v4.

This series removes alloc_vm_area, which was left over from the big
vmalloc interface rework.  It is a rather arkane interface, basicaly the
equivalent of get_vm_area + actually faulting in all PTEs in the allocated
area.  It was originally addeds for Xen (which isn't modular to start
with), and then grew users in zsmalloc and i915 which seems to mostly
qualify as abuses of the interface, especially for i915 as a random driver
should not set up PTE bits directly.


This patch (of 11):

 * Document that you can call vfree() on an address returned from vmap()
 * Remove the note about the minimum size -- the minimum size of a vmalloc
   allocation is one page
 * Add a Context: section
 * Fix capitalisation
 * Reword the prohibition on calling from NMI context to avoid a double
   negative

Link: https://lkml.kernel.org/r/20201002122204.1534411-1-hch@lst.de
Link: https://lkml.kernel.org/r/20201002122204.1534411-2-hch@lst.de
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmalloc.c |   21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

--- a/mm/vmalloc.c~mm-update-the-documentation-for-vfree
+++ a/mm/vmalloc.c
@@ -2321,20 +2321,21 @@ static void __vfree(const void *addr)
 }
 
 /**
- * vfree - release memory allocated by vmalloc()
- * @addr:  memory base address
+ * vfree - Release memory allocated by vmalloc()
+ * @addr:  Memory base address
  *
- * Free the virtually continuous memory area starting at @addr, as
- * obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
- * NULL, no operation is performed.
+ * Free the virtually continuous memory area starting at @addr, as obtained
+ * from one of the vmalloc() family of APIs.  This will usually also free the
+ * physical memory underlying the virtual allocation, but that memory is
+ * reference counted, so it will not be freed until the last user goes away.
  *
- * Must not be called in NMI context (strictly speaking, only if we don't
- * have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
- * conventions for vfree() arch-depenedent would be a really bad idea)
+ * If @addr is NULL, no operation is performed.
  *
+ * Context:
  * May sleep if called *not* from interrupt context.
- *
- * NOTE: assumes that the object at @addr has a size >= sizeof(llist_node)
+ * Must not be called in NMI context (strictly speaking, it could be
+ * if we have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
+ * conventions for vfree() arch-depenedent would be a really bad idea).
  */
 void vfree(const void *addr)
 {
_

  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-17 23:13 incoming Andrew Morton
2020-10-17 23:13 ` [patch 01/40] ia64: fix build error with !COREDUMP Andrew Morton
2020-10-17 23:13 ` [patch 02/40] mm, memcg: rework remote charging API to support nesting Andrew Morton
2020-10-17 23:13 ` [patch 03/40] mm: kmem: move memcg_kmem_bypass() calls to get_mem/obj_cgroup_from_current() Andrew Morton
2020-10-17 23:13 ` [patch 04/40] mm: kmem: remove redundant checks from get_obj_cgroup_from_current() Andrew Morton
2020-10-17 23:13 ` [patch 05/40] mm: kmem: prepare remote memcg charging infra for interrupt contexts Andrew Morton
2020-10-17 23:13 ` [patch 06/40] mm: kmem: enable kernel memcg accounting from " Andrew Morton
2020-10-17 23:13 ` [patch 07/40] mm/memory-failure: remove a wrapper for alloc_migration_target() Andrew Morton
2020-10-17 23:14 ` [patch 08/40] mm/memory_hotplug: " Andrew Morton
2020-10-17 23:14 ` [patch 09/40] mm/migrate: avoid possible unnecessary process right check in kernel_move_pages() Andrew Morton
2020-10-17 23:14 ` [patch 10/40] mm/mmap: add inline vma_next() for readability of mmap code Andrew Morton
2020-10-17 23:14 ` [patch 11/40] mm/mmap: add inline munmap_vma_range() for code readability Andrew Morton
2020-10-17 23:14 ` [patch 12/40] mm/gup_benchmark: take the mmap lock around GUP Andrew Morton
2020-10-17 23:14 ` [patch 13/40] binfmt_elf: take the mmap lock around find_extend_vma() Andrew Morton
2020-10-17 23:14 ` [patch 14/40] mm/gup: assert that the mmap lock is held in __get_user_pages() Andrew Morton
2020-10-17 23:14 ` [patch 15/40] mm/gup_benchmark: rename to mm/gup_test Andrew Morton
2020-10-17 23:14 ` [patch 16/40] selftests/vm: use a common gup_test.h Andrew Morton
2020-10-17 23:14 ` [patch 17/40] selftests/vm: rename run_vmtests --> run_vmtests.sh Andrew Morton
2020-10-17 23:14 ` [patch 18/40] selftests/vm: minor cleanup: Makefile and gup_test.c Andrew Morton
2020-10-17 23:14 ` [patch 19/40] selftests/vm: only some gup_test items are really benchmarks Andrew Morton
2020-10-17 23:14 ` [patch 20/40] selftests/vm: gup_test: introduce the dump_pages() sub-test Andrew Morton
2020-10-17 23:14 ` [patch 21/40] selftests/vm: run_vmtests.sh: update and clean up gup_test invocation Andrew Morton
2020-10-17 23:14 ` [patch 22/40] selftests/vm: hmm-tests: remove the libhugetlbfs dependency Andrew Morton
2020-10-17 23:14 ` [patch 23/40] selftests/vm: 10x speedup for hmm-tests Andrew Morton
2020-10-17 23:14 ` [patch 24/40] mm/madvise: pass mm to do_madvise Andrew Morton
2020-10-17 23:14 ` [patch 25/40] pid: move pidfd_get_pid() to pid.c Andrew Morton
2020-10-17 23:14 ` [patch 26/40] mm/madvise: introduce process_madvise() syscall: an external memory hinting API Andrew Morton
2020-10-17 23:15 ` Andrew Morton [this message]
2020-10-17 23:15 ` [patch 28/40] mm: add a VM_MAP_PUT_PAGES flag for vmap Andrew Morton
2020-10-17 23:15 ` [patch 29/40] mm: add a vmap_pfn function Andrew Morton
2020-10-17 23:15 ` [patch 30/40] mm: allow a NULL fn callback in apply_to_page_range Andrew Morton
2020-10-17 23:15 ` [patch 31/40] zsmalloc: switch from alloc_vm_area to get_vm_area Andrew Morton
2020-10-17 23:15 ` [patch 32/40] drm/i915: use vmap in shmem_pin_map Andrew Morton
2020-10-17 23:15 ` [patch 33/40] drm/i915: stop using kmap in i915_gem_object_map Andrew Morton
2020-10-17 23:15 ` [patch 34/40] drm/i915: use vmap " Andrew Morton
2020-10-17 23:15 ` [patch 35/40] xen/xenbus: use apply_to_page_range directly in xenbus_map_ring_pv Andrew Morton
2020-10-17 23:15 ` [patch 36/40] x86/xen: open code alloc_vm_area in arch_gnttab_valloc Andrew Morton
2020-10-17 23:15 ` [patch 37/40] mm: remove alloc_vm_area Andrew Morton
2020-10-17 23:15 ` [patch 38/40] mm: cleanup the gfp_mask handling in __vmalloc_area_node Andrew Morton
2020-10-17 23:15 ` [patch 39/40] mm: remove the filename in the top of file comment in vmalloc.c Andrew Morton
2020-10-17 23:15 ` [patch 40/40] mm: remove duplicate include statement in mmu.c Andrew Morton

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