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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, ben.widawsky@intel.com,
	linux-mm@kvack.org, mm-commits@vger.kernel.org,
	torvalds@linux-foundation.org
Subject: [patch 10/25] mm: add comments on pglist_data zones
Date: Wed, 10 Jun 2020 18:41:50 -0700	[thread overview]
Message-ID: <20200611014150.9MNWkw05i%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200610184053.3fa7368ab80e23bfd44de71f@linux-foundation.org>

From: Ben Widawsky <ben.widawsky@intel.com>
Subject: mm: add comments on pglist_data zones

While making other modifications it was easy to confuse the two struct
members node_zones and node_zonelists.  For those already familiar with
the code, this might seem to be a silly patch, but it's quite helpful to
disambiguate the similar-sounding fields

While here, add a small comment on why nr_zones isn't simply MAX_NR_ZONES

Link: http://lkml.kernel.org/r/20200520205443.2757414-1-ben.widawsky@intel.com
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mmzone.h |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/include/linux/mmzone.h~mm-add-comments-on-pglist_data-zones
+++ a/include/linux/mmzone.h
@@ -660,9 +660,21 @@ struct deferred_split {
  * per-zone basis.
  */
 typedef struct pglist_data {
+	/*
+	 * node_zones contains just the zones for THIS node. Not all of the
+	 * zones may be populated, but it is the full list. It is referenced by
+	 * this node's node_zonelists as well as other node's node_zonelists.
+	 */
 	struct zone node_zones[MAX_NR_ZONES];
+
+	/*
+	 * node_zonelists contains references to all zones in all nodes.
+	 * Generally the first zones will be references to this node's
+	 * node_zones.
+	 */
 	struct zonelist node_zonelists[MAX_ZONELISTS];
-	int nr_zones;
+
+	int nr_zones; /* number of populated zones in this node */
 #ifdef CONFIG_FLAT_NODE_MEM_MAP	/* means !SPARSEMEM */
 	struct page *node_mem_map;
 #ifdef CONFIG_PAGE_EXTENSION
_


  parent reply	other threads:[~2020-06-11  1:41 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11  1:40 incoming Andrew Morton
2020-06-11  1:41 ` [patch 01/25] khugepaged: selftests: fix timeout condition in wait_for_scan() Andrew Morton
2020-06-11  1:41 ` [patch 02/25] scripts/spelling: add a few more typos Andrew Morton
2020-06-11  1:41 ` [patch 03/25] kcov: check kcov_softirq in kcov_remote_stop() Andrew Morton
2020-06-11  1:41 ` [patch 04/25] lib/lz4/lz4_decompress.c: document deliberate use of `&' Andrew Morton
2020-06-11  1:41 ` [patch 05/25] nilfs2: fix null pointer dereference at nilfs_segctor_do_construct() Andrew Morton
2020-06-11  1:41 ` [patch 06/25] checkpatch: correct check for kernel parameters doc Andrew Morton
2020-06-11  1:41 ` [patch 07/25] lib: fix bitmap_parse() on 64-bit big endian archs Andrew Morton
2020-06-11  1:41 ` [patch 08/25] mm/debug_vm_pgtable: fix kernel crash by checking for THP support Andrew Morton
2020-06-11  1:41 ` [patch 09/25] ocfs2: fix spelling mistake and grammar Andrew Morton
2020-06-11  1:41 ` Andrew Morton [this message]
2020-06-11  1:41 ` [patch 11/25] lib: test get_count_order/long in test_bitops.c Andrew Morton
2020-06-11  1:41 ` [patch 12/25] stacktrace: cleanup inconsistent variable type Andrew Morton
2020-06-11  1:41 ` [patch 13/25] kernel: move use_mm/unuse_mm to kthread.c Andrew Morton
2020-06-11  1:42 ` [patch 14/25] " Andrew Morton
2020-06-11  1:42 ` [patch 15/25] kernel: better document the use_mm/unuse_mm API contract Andrew Morton
2020-06-11  1:42 ` [patch 16/25] kernel: set USER_DS in kthread_use_mm Andrew Morton
2020-06-11  1:42 ` [patch 17/25] mm/madvise: pass task and mm to do_madvise Andrew Morton
2020-06-11  1:42 ` [patch 18/25] mm/madvise: introduce process_madvise() syscall: an external memory hinting API Andrew Morton
2020-06-11  1:42 ` [patch 19/25] mm/madvise: check fatal signal pending of target process Andrew Morton
2020-06-11  1:42 ` [patch 20/25] pid: move pidfd_get_pid() to pid.c Andrew Morton
2020-06-11  1:42 ` [patch 21/25] mm/madvise: support both pid and pidfd for process_madvise Andrew Morton
2020-06-11  1:42 ` [patch 22/25] mm/madvise: allow KSM hints for remote API Andrew Morton
2020-06-11  1:42 ` [patch 23/25] mm: support vector address ranges for process_madvise Andrew Morton
2020-06-11  1:42 ` [patch 24/25] mm: use only pidfd for process_madvise syscall Andrew Morton
2020-06-11  2:09   ` Linus Torvalds
2020-06-11  3:10     ` Minchan Kim
2020-06-11  1:42 ` [patch 25/25] mm/madvise.c: remove duplicated include Andrew Morton

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