Sometimes the readout of /sys/kernel/debug/swiotlb/io_tlb_used and io_tlb_used_hiwater can be a huge number (e.g. 18446744073709551615), which is actually a negative number if we use "%ld" to print the number.
When swiotlb_create_default_debugfs() is running from late_initcall, mem->total_used may already be non-zero, because the storage driver may have already started to perform I/O operations: if the storage driver is built-in, its probe() callback is called before late_initcall.
swiotlb_create_debugfs_files() should not blindly set mem->total_used and mem->used_hiwater to 0; actually it doesn't have to initialize the fields at all, because the fields, as part of the global struct io_tlb_default_mem, have been implicitly initialized to zero.
Also don't explicitly set mem->transient_nslabs to 0.
Fixes: 8b0977ecc8b3 ("swiotlb: track and report io_tlb_used high water marks in debugfs") Fixes: 02e765697038 ("swiotlb: add debugfs to track swiotlb transient pool usage") Cc: stable@vger.kernel.org Signed-off-by: Dexuan Cui decui@microsoft.com --- kernel/dma/swiotlb.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 86fe172b5958..4a9f02c13da6 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1647,9 +1647,6 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_hiwater, io_tlb_hiwater_get, static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem, const char *dirname) { - atomic_long_set(&mem->total_used, 0); - atomic_long_set(&mem->used_hiwater, 0); - mem->debugfs = debugfs_create_dir(dirname, io_tlb_default_mem.debugfs); if (!mem->nslabs) return; @@ -1660,7 +1657,6 @@ static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem, debugfs_create_file("io_tlb_used_hiwater", 0600, mem->debugfs, mem, &fops_io_tlb_hiwater); #ifdef CONFIG_SWIOTLB_DYNAMIC - atomic_long_set(&mem->transient_nslabs, 0); debugfs_create_file("io_tlb_transient_nslabs", 0400, mem->debugfs, mem, &fops_io_tlb_transient_used); #endif