Vlastimil,
with commit 8ea1d2a1985a7ae096e ("mm, frontswap: convert frontswap_enabled to static key")
kmemleak complains about a memory leak in swapon
unreferenced object 0x3e09ba56000 (size 32112640):
comm "swapon", pid 7852, jiffies 4294968787 (age 1490.770s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000003a2504>] __vmalloc_node_range+0x194/0x2d8
[<00000000003a2918>] vzalloc+0x58/0x68
[<00000000003b0af0>] SyS_swapon+0xd60/0x12f8
[<0000000000a3dc2e>] system_call+0xd6/0x270
[<ffffffffffffffff>] 0xffffffffffffffff
Turns out kmemleak is right. We now allocate the frontswap map depending on the kernel config
(and no longer on the enablement)
swapfile.c:
[...]
if (IS_ENABLED(CONFIG_FRONTSWAP))
frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long));
but later on this is passed along
--> enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
and ignored if frontswap is disabled
--> frontswap_init(p->type, frontswap_map);
static inline void frontswap_init(unsigned type, unsigned long *map)
{
if (frontswap_enabled())
__frontswap_init(type, map);
}
Thing is, that frontswap map is never freed.
Christian
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