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mm: memory-failure: fix potential unexpected return value from unpoison_memory() 

If unpoison_memory() fails to clear page hwpoisoned flag, return value ret
is expected to be -EBUSY.  But when get_hwpoison_page() returns 1 and
fails to clear page hwpoisoned flag due to races, return value will be
unexpected 1 leading to users being confused.  And there's a code smell
that the variable "ret" is used not only to save the return value of
unpoison_memory(), but also the return value from get_hwpoison_page(). 
Make a further cleanup by using another auto-variable solely to save the
return value of get_hwpoison_page() as suggested by Naoya.

Link: https://lkml.kernel.org/r/20230727115643.639741-3-linmiaohe@huawei.com
Fixes: bf181c5825 ("mm/hwpoison: fix unpoison_memory()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2023-07-27 19:56:41 +08:00 committed by Andrew Morton
parent f985fc3220
commit f29623e4a5
1 changed files with 9 additions and 10 deletions
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19
mm/memory-failure.c
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@ -2466,7 +2466,7 @@ int unpoison_memory(unsigned long pfn)
{
struct folio *folio;
struct page *p;
int ret = -EBUSY;
int ret = -EBUSY, ghp;
unsigned long count = 1;
bool huge = false;
static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
@ -2514,29 +2514,28 @@ int unpoison_memory(unsigned long pfn)
if (folio_test_slab(folio) || PageTable(&folio->page) || folio_test_reserved(folio))
goto unlock_mutex;
ret = get_hwpoison_page(p, MF_UNPOISON);
if (!ret) {
ghp = get_hwpoison_page(p, MF_UNPOISON);
if (!ghp) {
if (PageHuge(p)) {
huge = true;
count = folio_free_raw_hwp(folio, false);
if (count == 0) {
ret = -EBUSY;
if (count == 0)
goto unlock_mutex;
}
}
ret = folio_test_clear_hwpoison(folio) ? 0 : -EBUSY;
} else if (ret < 0) {
if (ret == -EHWPOISON) {
} else if (ghp < 0) {
if (ghp == -EHWPOISON) {
ret = put_page_back_buddy(p) ? 0 : -EBUSY;
} else
} else {
ret = ghp;
unpoison_pr_info("Unpoison: failed to grab page %#lx\n",
pfn, &unpoison_rs);
}
} else {
if (PageHuge(p)) {
huge = true;
count = folio_free_raw_hwp(folio, false);
if (count == 0) {
ret = -EBUSY;
folio_put(folio);
goto unlock_mutex;
}