Hello Carlos Maiolino,
The patch 9a9f8f590f6d: "shmem: quota support" from Jul 25, 2023
(linux-next), leads to the following Smatch static checker warning:
fs/quota/dquot.c:1271 flush_warnings()
warn: sleeping in atomic context
fs/quota/dquot.c
1261 static void flush_warnings(struct dquot_warn *warn)
1262 {
1263 int i;
1264
1265 for (i = 0; i < MAXQUOTAS; i++) {
1266 if (warn[i].w_type == QUOTA_NL_NOWARN)
1267 continue;
1268 #ifdef CONFIG_PRINT_QUOTA_WARNING
1269 print_warning(&warn[i]);
1270 #endif
--> 1271 quota_send_warning(warn[i].w_dq_id,
1272 warn[i].w_sb->s_dev, warn[i].w_type);
The quota_send_warning() function does GFP_NOFS allocations, which don't
touch the fs but can still sleep. GFP_ATOMIC or GFP_NOWAIT don't sleep.
1273 }
1274 }
The call trees that Smatch is worried about are listed. The "disables
preempt" functions take the spin_lock_irq(&info->lock) before calling
shmem_recalc_inode().
shmem_charge() <- disables preempt
shmem_uncharge() <- disables preempt
shmem_undo_range() <- disables preempt
shmem_getattr() <- disables preempt
shmem_writepage() <- disables preempt
shmem_set_folio_swapin_error() <- disables preempt
shmem_swapin_folio() <- disables preempt
shmem_get_folio_gfp() <- disables preempt
-> shmem_recalc_inode()
-> shmem_inode_unacct_blocks()
-> dquot_free_block_nodirty()
-> dquot_free_space_nodirty()
-> __dquot_free_space()
-> flush_warnings()
regards,
dan carpenter
