diff options
| author | Hugh Dickins <hughd@google.com> | 2023-07-25 16:45:10 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2023-08-09 09:15:40 +0200 |
| commit | 509f006932de7556d48eaa7afcd02dcf1ca9a3e9 (patch) | |
| tree | 54b4f72158590dca8035163a57e807f4e1143258 /mm/huge_memory.c | |
| parent | de4c0e7ca8b526a82ff7e5ee5533787bb6d01724 (diff) | |
shmem: fix quota lock nesting in huge hole handling
i_pages lock nests inside i_lock, but shmem_charge() and shmem_uncharge()
were being called from THP splitting or collapsing while i_pages lock was
held, and now go on to call dquot_alloc_block_nodirty() which takes
i_lock to update i_blocks.
We may well want to take i_lock out of this path later, in the non-quota
case even if it's left in the quota case (or perhaps use i_lock instead
of shmem's info->lock throughout); but don't get into that at this time.
Move the shmem_charge() and shmem_uncharge() calls out from under i_pages
lock, accounting the full batch of holes in a single call.
Still pass the pages argument to shmem_uncharge(), but it happens now to
be unused: shmem_recalc_inode() is designed to account for clean pages
freed behind shmem's back, so it gets the accounting right by itself;
then the later call to shmem_inode_unacct_blocks() led to imbalance
(that WARN_ON(inode->i_blocks) in shmem_evict_inode()).
Reported-by: syzbot+38ca19393fb3344f57e6@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/0000000000008e62f40600bfe080@google.com/
Reported-by: syzbot+440ff8cca06ee7a1d4db@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/00000000000076a7840600bfb6e8@google.com/
Signed-off-by: Hugh Dickins <hughd@google.com>
Tested-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Message-Id: <20230725144510.253763-8-cem@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index eb3678360b97..d301c323c69a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2521,7 +2521,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, struct address_space *swap_cache = NULL; unsigned long offset = 0; unsigned int nr = thp_nr_pages(head); - int i; + int i, nr_dropped = 0; /* complete memcg works before add pages to LRU */ split_page_memcg(head, nr); @@ -2546,7 +2546,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, struct folio *tail = page_folio(head + i); if (shmem_mapping(head->mapping)) - shmem_uncharge(head->mapping->host, 1); + nr_dropped++; else if (folio_test_clear_dirty(tail)) folio_account_cleaned(tail, inode_to_wb(folio->mapping->host)); @@ -2583,6 +2583,8 @@ static void __split_huge_page(struct page *page, struct list_head *list, } local_irq_enable(); + if (nr_dropped) + shmem_uncharge(head->mapping->host, nr_dropped); remap_page(folio, nr); if (PageSwapCache(head)) { |