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mm, page_owner: fix off-by-one error in __set_page_owner_handle()

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Patch series "followups to debug_pagealloc improvements through
page_owner", v3.

These are followups to [1] which made it to Linus meanwhile.  Patches 1
and 3 are based on Kirill's review, patch 2 on KASAN request [2].  It
would be nice if all of this made it to 5.4 with [1] already there (or
at least Patch 1).

This patch (of 3):

As noted by Kirill, commit 7e2f2a0cd1 ("mm, page_owner: record page
owner for each subpage") has introduced an off-by-one error in
__set_page_owner_handle() when looking up page_ext for subpages.  As a
result, the head page page_owner info is set twice, while for the last
tail page, it's not set at all.

Fix this and also make the code more efficient by advancing the page_ext
pointer we already have, instead of calling lookup_page_ext() for each
subpage.  Since the full size of struct page_ext is not known at compile
time, we can't use a simple page_ext++ statement, so introduce a
page_ext_next() inline function for that.

Link: http://lkml.kernel.org/r/20190930122916.14969-2-vbabka@suse.cz
Fixes: 7e2f2a0cd1 ("mm, page_owner: record page owner for each subpage")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Reported-by: Miles Chen <miles.chen@mediatek.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vlastimil Babka
2019-10-14 14:11:40 -07:00
committed by Linus Torvalds
parent 2abd839aa7
commit 5556cfe8d9
3 changed files with 24 additions and 22 deletions
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23
mm/page_ext.c
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@@ -67,8 +67,9 @@ static struct page_ext_operations *page_ext_ops[] = {
#endif
};
unsigned long page_ext_size = sizeof(struct page_ext);
static unsigned long total_usage;
static unsigned long extra_mem;
static bool __init invoke_need_callbacks(void)
{
@@ -78,9 +79,8 @@ static bool __init invoke_need_callbacks(void)
for (i = 0; i < entries; i++) {
if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
page_ext_ops[i]->offset = sizeof(struct page_ext) +
extra_mem;
extra_mem += page_ext_ops[i]->size;
page_ext_ops[i]->offset = page_ext_size;
page_ext_size += page_ext_ops[i]->size;
need = true;
}
}
@@ -99,14 +99,9 @@ static void __init invoke_init_callbacks(void)
}
}
static unsigned long get_entry_size(void)
{
return sizeof(struct page_ext) + extra_mem;
}
static inline struct page_ext *get_entry(void *base, unsigned long index)
{
return base + get_entry_size() * index;
return base + page_ext_size * index;
}
#if !defined(CONFIG_SPARSEMEM)
@@ -156,7 +151,7 @@ static int __init alloc_node_page_ext(int nid)
!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
nr_pages += MAX_ORDER_NR_PAGES;
table_size = get_entry_size() * nr_pages;
table_size = page_ext_size * nr_pages;
base = memblock_alloc_try_nid(
table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
@@ -234,7 +229,7 @@ static int __meminit init_section_page_ext(unsigned long pfn, int nid)
if (section->page_ext)
return 0;
table_size = get_entry_size() * PAGES_PER_SECTION;
table_size = page_ext_size * PAGES_PER_SECTION;
base = alloc_page_ext(table_size, nid);
/*
@@ -254,7 +249,7 @@ static int __meminit init_section_page_ext(unsigned long pfn, int nid)
* we need to apply a mask.
*/
pfn &= PAGE_SECTION_MASK;
section->page_ext = (void *)base - get_entry_size() * pfn;
section->page_ext = (void *)base - page_ext_size * pfn;
total_usage += table_size;
return 0;
}
@@ -267,7 +262,7 @@ static void free_page_ext(void *addr)
struct page *page = virt_to_page(addr);
size_t table_size;
table_size = get_entry_size() * PAGES_PER_SECTION;
table_size = page_ext_size * PAGES_PER_SECTION;
BUG_ON(PageReserved(page));
kmemleak_free(addr);