[lkml]   [2019]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v6 39/49] soc: fsl: qe: refactor cpm_muram_alloc_common to prevent BUG on error path
If the kmalloc() fails, we try to undo the gen_pool allocation we've
just done. Unfortunately, start has already been modified to subtract
the GENPOOL_OFFSET bias, so we're freeing something that very likely
doesn't exist in the gen_pool, meaning we hit the

kernel BUG at lib/genalloc.c:399!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
[<803fd0e8>] (gen_pool_free) from [<80426bc8>] (cpm_muram_alloc_common+0xb0/0xc8)
[<80426bc8>] (cpm_muram_alloc_common) from [<80426c28>] (cpm_muram_alloc+0x48/0x80)
[<80426c28>] (cpm_muram_alloc) from [<80428214>] (ucc_slow_init+0x110/0x4f0)
[<80428214>] (ucc_slow_init) from [<8044a718>] (qe_uart_request_port+0x3c/0x1d8)

(this was tested by just injecting a random failure by adding
"|| (get_random_int()&7) == 0" to the "if (!entry)" condition).

Refactor the code so we do the kmalloc() first, meaning that's the
thing that needs undoing in case gen_pool_alloc_algo() then
fails. This allows a later cleanup to move the locking from the
callers into the _common function, keeping the kmalloc() out of the
critical region and then, hopefully (if all the muram_alloc callers
allow) change it to a GFP_KERNEL allocation.

Reviewed-by: Timur Tabi <>
Signed-off-by: Rasmus Villemoes <>
drivers/soc/fsl/qe/qe_common.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/soc/fsl/qe/qe_common.c b/drivers/soc/fsl/qe/qe_common.c
index dcb267567d76..a81a1a79f1ca 100644
--- a/drivers/soc/fsl/qe/qe_common.c
+++ b/drivers/soc/fsl/qe/qe_common.c
@@ -119,23 +119,21 @@ static s32 cpm_muram_alloc_common(unsigned long size,
struct muram_block *entry;
s32 start;

+ entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+ if (!entry)
+ return -ENOMEM;
start = gen_pool_alloc_algo(muram_pool, size, algo, data);
- if (!start)
- goto out2;
+ if (!start) {
+ kfree(entry);
+ return -ENOMEM;
+ }
start = start - GENPOOL_OFFSET;
memset_io(cpm_muram_addr(start), 0, size);
- entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
- if (!entry)
- goto out1;
entry->start = start;
entry->size = size;
list_add(&entry->head, &muram_block_list);

return start;
- gen_pool_free(muram_pool, start, size);
- return -ENOMEM;

 \ /
  Last update: 2019-11-28 15:59    [W:0.175 / U:0.480 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site