linux/include
Pierre Barre e21d451a82 9p: Use kvmalloc for message buffers on supported transports
While developing a 9P server (https://github.com/Barre/ZeroFS) and
testing it under high-load, I was running into allocation failures.
The failures occur even with plenty of free memory available because
kmalloc requires contiguous physical memory.

This results in errors like:
ls: page allocation failure: order:7, mode:0x40c40(GFP_NOFS|__GFP_COMP)

This patch introduces a transport capability flag (supports_vmalloc)
that indicates whether a transport can work with vmalloc'd buffers
(non-physically contiguous memory). Transports requiring DMA should
leave this flag as false.

The fd-based transports (tcp, unix, fd) set this flag to true, and
p9_fcall_init will use kvmalloc instead of kmalloc for these
transports. This allows the allocator to fall back to vmalloc when
contiguous physical memory is not available.

Additionally, if kmem_cache_alloc fails, the code falls back to
kvmalloc for transports that support it.

Signed-off-by: Pierre Barre <pierre@barre.sh>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Message-ID: <d2017c29-11fb-44a5-bd0f-4204329bbefb@app.fastmail.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2025-11-03 16:41:24 +09:00
..
acpi More power management updates for 6.18-rc1 2025-10-07 09:39:51 -07:00
asm-generic hyperv-next for v6.18 2025-10-07 08:40:15 -07:00
clocksource
crypto This update includes the following changes: 2025-10-04 14:59:29 -07:00
cxl
drm drm/gpuvm: Fix kernel-doc warning for drm_gpuvm_map_req.map 2025-10-15 18:37:05 +02:00
dt-bindings There's a bunch of patches here across drivers/clk/ to migrate drivers to use 2025-10-07 09:28:37 -07:00
hyperv hyperv: Remove the spurious null directive line 2025-10-02 21:21:24 +00:00
keys KEYS: trusted_tpm1: Move private functionality out of public header 2025-09-27 21:05:06 +03:00
kunit linux_kselftest-kunit-6.18-rc1 2025-10-01 19:15:11 -07:00
kvm KVM: arm64: Kill leftovers of ad-hoc timer userspace access 2025-10-13 14:42:41 +01:00
linux hid-for-linus-2025101701 2025-10-18 08:18:18 -10:00
math-emu
media
memory
misc
net 9p: Use kvmalloc for message buffers on supported transports 2025-11-03 16:41:24 +09:00
pcmcia
ras
rdma
rv kernel-6.18-rc1.clone3 2025-09-29 10:36:50 -07:00
scsi SCSI misc on 20251002 2025-10-03 19:17:48 -07:00
soc There's a bunch of patches here across drivers/clk/ to migrate drivers to use 2025-10-07 09:28:37 -07:00
sound ASoC: tas2781: Support more newly-released amplifiers tas58xx in the driver 2025-10-13 11:08:09 +01:00
target
trace dma-mapping fixes for Linux 6.18: 2025-10-07 12:48:06 -07:00
uapi ARM: 2025-10-18 07:07:14 -10:00
ufs scsi: ufs: core: Include UTP error in INT_FATAL_ERRORS 2025-09-30 16:10:29 -04:00
vdso Updates for the VDSO subsystem: 2025-09-30 16:58:21 -07:00
video
xen
Kbuild