diff options
| author | Miaohe Lin <linmiaohe@huawei.com> | 2022-05-19 20:50:26 +0800 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-05-27 09:33:45 -0700 |
| commit | 9f186f9e5fa9ebdaef909fd45f825a6ce281f13c (patch) | |
| tree | 3deb7a4f3b077644c3a686974aa37da259899299 /include/linux | |
| parent | f079a020ba95b568329806aa13c62e6103cade3c (diff) | |
mm/swapfile: unuse_pte can map random data if swap read fails
Patch series "A few fixup patches for mm", v4.
This series contains a few patches to avoid mapping random data if swap
read fails and fix lost swap bits in unuse_pte. Also we free hwpoison and
swapin error entry in madvise_free_pte_range and so on. More details can
be found in the respective changelogs.
This patch (of 5):
There is a bug in unuse_pte(): when swap page happens to be unreadable,
page filled with random data is mapped into user address space. In case
of error, a special swap entry indicating swap read fails is set to the
page table. So the swapcache page can be freed and the user won't end up
with a permanently mounted swap because a sector is bad. And if the page
is accessed later, the user process will be killed so that corrupted data
is never consumed. On the other hand, if the page is never accessed, the
user won't even notice it.
Link: https://lkml.kernel.org/r/20220519125030.21486-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220519125030.21486-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/swap.h | 7 | ||||
| -rw-r--r-- | include/linux/swapops.h | 10 |
2 files changed, 16 insertions, 1 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index f3ae17b43f20..0c0fed1b348f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -55,6 +55,10 @@ static inline int current_is_kswapd(void) * actions on faults. */ +#define SWP_SWAPIN_ERROR_NUM 1 +#define SWP_SWAPIN_ERROR (MAX_SWAPFILES + SWP_HWPOISON_NUM + \ + SWP_MIGRATION_NUM + SWP_DEVICE_NUM + \ + SWP_PTE_MARKER_NUM) /* * PTE markers are used to persist information onto PTEs that are mapped with * file-backed memories. As its name "PTE" hints, it should only be applied to @@ -120,7 +124,8 @@ static inline int current_is_kswapd(void) #define MAX_SWAPFILES \ ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \ - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - SWP_PTE_MARKER_NUM) + SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \ + SWP_PTE_MARKER_NUM - SWP_SWAPIN_ERROR_NUM) /* * Magic header for a swap area. The first part of the union is diff --git a/include/linux/swapops.h b/include/linux/swapops.h index fe220df499f1..f24775b41880 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -108,6 +108,16 @@ static inline void *swp_to_radix_entry(swp_entry_t entry) return xa_mk_value(entry.val); } +static inline swp_entry_t make_swapin_error_entry(struct page *page) +{ + return swp_entry(SWP_SWAPIN_ERROR, page_to_pfn(page)); +} + +static inline int is_swapin_error_entry(swp_entry_t entry) +{ + return swp_type(entry) == SWP_SWAPIN_ERROR; +} + #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset) { |