Provide unified API rather than just calling kmem_cache_{alloc,free}_cached

[hygoni]

As Jens mentioned, there's no reason that
kmem_cache_{alloc,free}_cached should be separate API.

it seems better that kmem_cache_alloc calls _cached version when the cache is available.
Some calling contexts should be considered to that. and test is needed.

[hygoni]

I'm testing this with enabling SLAB_LOCKLESS_CACHE on every slab cache except boot cache.

But I get kernel panic:
[ 0.000000] traps: PANIC: double fault, error_code: 0xffffffff8e7e06f0
[ 0.000000] BUG: unable to handle page fault for address: fffffe000000a000
[ 0.000000] #PF: supervisor read access in kernel mode
[ 0.000000] #PF: error_code(0x0000) - not-present page
[ 0.000000] PGD 23fff2067 P4D 23fff2067 PUD 23fff1067 PMD 23ffef067 PTE 0
[ 0.000000] Oops: 0000 [#1] SMP PTI
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.0-rc2+ #3
[ 0.000000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/4
[ 0.000000] RIP: 0010:__die_header+0x19/0x6e
[ 0.000000] Code: e8 0c 7f 00 00 c7 43 50 00 00 00 00 e9 4b 5f 4e ff 8b 05 c7 10 14 0
[ 0.000000] RSP: 0000:fffffe0000009ee8 EFLAGS: 00010046
[ 0.000000] RAX: 0000000000000000 RBX: ffffffff8f815cde RCX: 0000000000000002
[ 0.000000] RDX: ffffffff8e7e06f0 RSI: fffffe000000a000 RDI: ffffffff9027e780
[ 0.000000] RBP: fffffe0000009f60 R08: ffffffff8fa55580 R09: 6666666666666666
[ 0.000000] R10: ffffffff8f815cde R11: 203a65646f635f72 R12: ffffffff8e7e06f0
[ 0.000000] R13: ffffffff8e7e06f0 R14: 0000000000000000 R15: 0000000000000000
[ 0.000000] FS: 0000000000000000(0000) GS:ffff8b1977c00000(0000) knlGS:0000000000000
[ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.000000] CR2: fffffe000000a000 CR3: 0000000229e0c000 CR4: 00000000000006b0
[ 0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 0.000000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 0.000000] Call Trace:
[ 0.000000] <#DF>
[ 0.000000] __die+0x12/0x24
[ 0.000000] die+0x25/0x40
[ 0.000000] ? kmem_cache_alloc_bulk+0xc0/0x220
[ 0.000000] exc_double_fault+0x119/0x130
[ 0.000000] asm_exc_double_fault+0x1e/0x40
[ 0.000000] WARNING: stack recursion on stack type 5
[ 0.000000] WARNING: can't access registers at asm_exc_double_fault+0x1e/0x40
[ 0.000000] ? __vunmap+0x220/0x220
[ 0.000000] ? kmem_cache_alloc_cached+0x7a/0xa0
[ 0.000000] </#DF>
[ 0.000000] ? __vunmap+0x220/0x220
[ 0.000000] ? kmem_cache_alloc_cached+0x7a/0xa0
[ 0.000000] ? vmalloc_init+0x137/0x19b
[ 0.000000] ? start_kernel+0x3b6/0x677
[ 0.000000] ? secondary_startup_64_no_verify+0xc2/0xcb
[ 0.000000] Modules linked in:
[ 0.000000] CR2: fffffe000000a000
[ 0.000000] random: get_random_bytes called from print_oops_end_marker+0x21/0x40 wit0
[ 0.000000] ---[ end trace 99145c9ed6df72af ]---
[ 0.000000] RIP: 0010:__die_header+0x19/0x6e
[ 0.000000] Code: e8 0c 7f 00 00 c7 43 50 00 00 00 00 e9 4b 5f 4e ff 8b 05 c7 10 14 0
[ 0.000000] RSP: 0000:fffffe0000009ee8 EFLAGS: 00010046
[ 0.000000] RAX: 0000000000000000 RBX: ffffffff8f815cde RCX: 0000000000000002
[ 0.000000] RDX: ffffffff8e7e06f0 RSI: fffffe000000a000 RDI: ffffffff9027e780
[ 0.000000] RBP: fffffe0000009f60 R08: ffffffff8fa55580 R09: 6666666666666666
[ 0.000000] R10: ffffffff8f815cde R11: 203a65646f635f72 R12: ffffffff8e7e06f0
[ 0.000000] R13: ffffffff8e7e06f0 R14: 0000000000000000 R15: 0000000000000000
[ 0.000000] FS: 0000000000000000(0000) GS:ffff8b1977c00000(0000) knlGS:0000000000000
[ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.000000] CR2: fffffe000000a000 CR3: 0000000229e0c000 CR4: 00000000000006b0
[ 0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 0.000000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 0.000000] Kernel panic - not syncing: Fatal exception in interrupt

[hygoni]

It was due to I called kmem_cache_alloc_cached even with GFP_KERNEL.

XD. That is fixed now.

[hygoni]

Wait, why does it matter?
The crash is because I called kmem_cache_alloc_bulk with GFP_KERNEL.

Seems I made wrong fix :<

[hygoni]

Things are good now