The patch titled Subject: lib/stackdepot: double DEPOT_POOLS_CAP if KASAN is enabled has been added to the -mm mm-hotfixes-unstable branch. Its filename is lib-stackdepot-double-depot_pools_cap-if-kasan-is-enabled.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Waiman Long longman@redhat.com Subject: lib/stackdepot: double DEPOT_POOLS_CAP if KASAN is enabled Date: Wed, 7 Aug 2024 12:52:28 -0400

When a wide variety of workloads are run on a debug kernel with KASAN enabled, the following warning may sometimes be printed.

[ 6818.650674] Stack depot reached limit capacity [ 6818.650730] WARNING: CPU: 1 PID: 272741 at lib/stackdepot.c:252 depot_alloc_stack+0x39e/0x3d0 : [ 6818.650907] Call Trace: [ 6818.650909] [<00047dd453d84b92>] depot_alloc_stack+0x3a2/0x3d0 [ 6818.650916] [<00047dd453d85254>] stack_depot_save_flags+0x4f4/0x5c0 [ 6818.650920] [<00047dd4535872c6>] kasan_save_stack+0x56/0x70 [ 6818.650924] [<00047dd453587328>] kasan_save_track+0x28/0x40 [ 6818.650927] [<00047dd45358a27a>] kasan_save_free_info+0x4a/0x70 [ 6818.650930] [<00047dd45358766a>] __kasan_slab_free+0x12a/0x1d0 [ 6818.650933] [<00047dd45350deb4>] kmem_cache_free+0x1b4/0x580 [ 6818.650938] [<00047dd452c520da>] __put_task_struct+0x24a/0x320 [ 6818.650945] [<00047dd452c6aee4>] delayed_put_task_struct+0x294/0x350 [ 6818.650949] [<00047dd452e9066a>] rcu_do_batch+0x6ea/0x2090 [ 6818.650953] [<00047dd452ea60f4>] rcu_core+0x474/0xa90 [ 6818.650956] [<00047dd452c780c0>] handle_softirqs+0x3c0/0xf90 [ 6818.650960] [<00047dd452c76fbe>] __irq_exit_rcu+0x35e/0x460 [ 6818.650963] [<00047dd452c79992>] irq_exit_rcu+0x22/0xb0 [ 6818.650966] [<00047dd454bd8128>] do_ext_irq+0xd8/0x120 [ 6818.650972] [<00047dd454c0ddd0>] ext_int_handler+0xb8/0xe8 [ 6818.650979] [<00047dd453589cf6>] kasan_check_range+0x236/0x2f0 [ 6818.650982] [<00047dd453378cf0>] filemap_get_pages+0x190/0xaa0 [ 6818.650986] [<00047dd453379940>] filemap_read+0x340/0xa70 [ 6818.650989] [<00047dd3d325d226>] xfs_file_buffered_read+0x2c6/0x400 [xfs] [ 6818.651431] [<00047dd3d325dfe2>] xfs_file_read_iter+0x2c2/0x550 [xfs] [ 6818.651663] [<00047dd45364710c>] vfs_read+0x64c/0x8c0 [ 6818.651669] [<00047dd453648ed8>] ksys_read+0x118/0x200 [ 6818.651672] [<00047dd452b6cf5a>] do_syscall+0x27a/0x380 [ 6818.651676] [<00047dd454bd7e74>] __do_syscall+0xf4/0x1a0 [ 6818.651680] [<00047dd454c0db58>] system_call+0x70/0x98

As KASAN is a big user of stackdepot, the current DEPOT_POOLS_CAP of 8192 may not be enough. Double DEPOT_POOLS_CAP if KASAN is enabled to avoid hitting this problem.

Also use the MIN() macro for defining DEPOT_MAX_POOLS to clarify the intention.

Link: https://lkml.kernel.org/r/20240807165228.1116831-1-longman@redhat.com Fixes: 02754e0a484a ("lib/stackdepot.c: bump stackdepot capacity from 16MB to 128MB") Signed-off-by: Waiman Long longman@redhat.com Cc: Andrey Konovalov andreyknvl@google.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

lib/stackdepot.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/lib/stackdepot.c~lib-stackdepot-double-depot_pools_cap-if-kasan-is-enabled +++ a/lib/stackdepot.c @@ -36,11 +36,12 @@ #include <linux/memblock.h> #include <linux/kasan-enabled.h>

-#define DEPOT_POOLS_CAP 8192 +/* KASAN is a big user of stackdepot, double the cap if KASAN is enabled */ +#define DEPOT_POOLS_CAP (8192 * (IS_ENABLED(CONFIG_KASAN) ? 2 : 1)) + /* The pool_index is offset by 1 so the first record does not have a 0 handle. */ #define DEPOT_MAX_POOLS \ - (((1LL << (DEPOT_POOL_INDEX_BITS)) - 1 < DEPOT_POOLS_CAP) ? \ - (1LL << (DEPOT_POOL_INDEX_BITS)) - 1 : DEPOT_POOLS_CAP) + MIN((1LL << (DEPOT_POOL_INDEX_BITS)) - 1, DEPOT_POOLS_CAP)

static bool stack_depot_disabled; static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT); _

Patches currently in -mm which might be from longman@redhat.com are

padata-fix-possible-divide-by-0-panic-in-padata_mt_helper.patch mm-memory-failure-use-raw_spinlock_t-in-struct-memory_failure_cpu.patch mm-memory-failure-use-raw_spinlock_t-in-struct-memory_failure_cpu-v3.patch lib-stackdepot-double-depot_pools_cap-if-kasan-is-enabled.patch watchdog-handle-the-enodev-failure-case-of-lockup_detector_delay_init-separately.patch