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ANDROID: mm/memory_hotplug: fix check for proper subsection removal

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When removing memory subsections, we need to ensure that subsections are
not in use or online before we try to remove them. Previously, we used
test_pages_isolated() which works only if pages were onlined and added to
a zone before. However, we should allow subsection addition and removal
without them being added to buddy i.e. onlined. test_pages_isolated() would
not help in such cases. Instead, check for valid offlined sections before
the subsections within can be allowed to be removed.

Bug: 170460867
Fixes: 417ac617ea ("ANDROID: mm/memory_hotplug: implement {add/remove}_memory_subsection")
Change-Id: I09b46582cd21e9e5370ebd5434209530edb89e58
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
This commit is contained in:
Sudarshan Rajagopalan
2021-02-04 19:28:34 -08:00
committed by Suren Baghdasaryan
parent 25b284fcf2
commit bbea47ac00
1 changed files with 19 additions and 2 deletions
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21
mm/memory_hotplug.c
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@@ -1828,6 +1828,22 @@ int remove_memory(int nid, u64 start, u64 size)
}
EXPORT_SYMBOL_GPL(remove_memory);
static bool __check_sections_offline(unsigned long start_pfn,
unsigned long nr_pages)
{
const unsigned long end_pfn = start_pfn + nr_pages;
unsigned long pfn, sec_nr;
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
sec_nr = pfn_to_section_nr(pfn);
if (!valid_section_nr(sec_nr) || online_section_nr(sec_nr))
return false;
}
return true;
}
int remove_memory_subsection(int nid, u64 start, u64 size)
{
if (size == memory_block_size_bytes())
@@ -1842,8 +1858,9 @@ int remove_memory_subsection(int nid, u64 start, u64 size)
mem_hotplug_begin();
if (test_pages_isolated(start, start + size, MEMORY_OFFLINE)) {
pr_err("%s: [%lx, %lx) PFNs are not isolated\n",
/* we cannot remove subsections that are invalid or online */
if(!__check_sections_offline(PHYS_PFN(start), size >> PAGE_SHIFT)) {
pr_err("%s: [%lx, %lx) sections are not offlined\n",
__func__, start, start + size);
mem_hotplug_done();
return -EBUSY;