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37554d48 SL |
1 | From 9da1b4ca02dcc2d7059c9f615dcd317d8fb28dd0 Mon Sep 17 00:00:00 2001 |
2 | From: Yue Hu <huyue2@yulong.com> | |
3 | Date: Mon, 13 May 2019 17:17:41 -0700 | |
4 | Subject: mm/cma.c: fix the bitmap status to show failed allocation reason | |
5 | ||
6 | [ Upstream commit 2b59e01a3aa665f751d1410b99fae9336bd424e1 ] | |
7 | ||
8 | Currently one bit in cma bitmap represents number of pages rather than | |
9 | one page, cma->count means cma size in pages. So to find available pages | |
10 | via find_next_zero_bit()/find_next_bit() we should use cma size not in | |
11 | pages but in bits although current free pages number is correct due to | |
12 | zero value of order_per_bit. Once order_per_bit is changed the bitmap | |
13 | status will be incorrect. | |
14 | ||
15 | The size input in cma_debug_show_areas() is not correct. It will | |
16 | affect the available pages at some position to debug the failure issue. | |
17 | ||
18 | This is an example with order_per_bit = 1 | |
19 | ||
20 | Before this change: | |
21 | [ 4.120060] cma: number of available pages: 1@93+4@108+7@121+7@137+7@153+7@169+7@185+7@201+3@213+3@221+3@229+3@237+3@245+3@253+3@261+3@269+3@277+3@285+3@293+3@301+3@309+3@317+3@325+19@333+15@369+512@512=> 638 free of 1024 total pages | |
22 | ||
23 | After this change: | |
24 | [ 4.143234] cma: number of available pages: 2@93+8@108+14@121+14@137+14@153+14@169+14@185+14@201+6@213+6@221+6@229+6@237+6@245+6@253+6@261+6@269+6@277+6@285+6@293+6@301+6@309+6@317+6@325+38@333+30@369=> 252 free of 1024 total pages | |
25 | ||
26 | Obviously the bitmap status before is incorrect. | |
27 | ||
28 | Link: http://lkml.kernel.org/r/20190320060829.9144-1-zbestahu@gmail.com | |
29 | Signed-off-by: Yue Hu <huyue2@yulong.com> | |
30 | Reviewed-by: Andrew Morton <akpm@linux-foundation.org> | |
31 | Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> | |
32 | Cc: Ingo Molnar <mingo@kernel.org> | |
33 | Cc: Vlastimil Babka <vbabka@suse.cz> | |
34 | Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> | |
35 | Cc: Randy Dunlap <rdunlap@infradead.org> | |
36 | Cc: Laura Abbott <labbott@redhat.com> | |
37 | Signed-off-by: Andrew Morton <akpm@linux-foundation.org> | |
38 | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> | |
39 | Signed-off-by: Sasha Levin <sashal@kernel.org> | |
40 | --- | |
41 | mm/cma.c | 19 +++++++++++-------- | |
42 | 1 file changed, 11 insertions(+), 8 deletions(-) | |
43 | ||
44 | diff --git a/mm/cma.c b/mm/cma.c | |
45 | index 6ce6e22f82d9..476dfe13a701 100644 | |
46 | --- a/mm/cma.c | |
47 | +++ b/mm/cma.c | |
48 | @@ -371,23 +371,26 @@ err: | |
49 | #ifdef CONFIG_CMA_DEBUG | |
50 | static void cma_debug_show_areas(struct cma *cma) | |
51 | { | |
52 | - unsigned long next_zero_bit, next_set_bit; | |
53 | + unsigned long next_zero_bit, next_set_bit, nr_zero; | |
54 | unsigned long start = 0; | |
55 | - unsigned int nr_zero, nr_total = 0; | |
56 | + unsigned long nr_part, nr_total = 0; | |
57 | + unsigned long nbits = cma_bitmap_maxno(cma); | |
58 | ||
59 | mutex_lock(&cma->lock); | |
60 | pr_info("number of available pages: "); | |
61 | for (;;) { | |
62 | - next_zero_bit = find_next_zero_bit(cma->bitmap, cma->count, start); | |
63 | - if (next_zero_bit >= cma->count) | |
64 | + next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start); | |
65 | + if (next_zero_bit >= nbits) | |
66 | break; | |
67 | - next_set_bit = find_next_bit(cma->bitmap, cma->count, next_zero_bit); | |
68 | + next_set_bit = find_next_bit(cma->bitmap, nbits, next_zero_bit); | |
69 | nr_zero = next_set_bit - next_zero_bit; | |
70 | - pr_cont("%s%u@%lu", nr_total ? "+" : "", nr_zero, next_zero_bit); | |
71 | - nr_total += nr_zero; | |
72 | + nr_part = nr_zero << cma->order_per_bit; | |
73 | + pr_cont("%s%lu@%lu", nr_total ? "+" : "", nr_part, | |
74 | + next_zero_bit); | |
75 | + nr_total += nr_part; | |
76 | start = next_zero_bit + nr_zero; | |
77 | } | |
78 | - pr_cont("=> %u free of %lu total pages\n", nr_total, cma->count); | |
79 | + pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count); | |
80 | mutex_unlock(&cma->lock); | |
81 | } | |
82 | #else | |
83 | -- | |
84 | 2.20.1 | |
85 |