diff options
| author | Pierre Barre <pierre@barre.sh> | 2025-10-16 15:58:36 +0200 |
|---|---|---|
| committer | Dominique Martinet <asmadeus@codewreck.org> | 2025-11-03 16:41:24 +0900 |
| commit | e21d451a82f39e91b7635c4fc3ff5ac082873ec3 (patch) | |
| tree | c5c85f3847d891ebb60e0718e4298896b7ca9bae /include | |
| parent | 43c36a56ccf6d9b07b4b3f4f614756e687dcdc01 (diff) | |
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>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/9p/transport.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/net/9p/transport.h b/include/net/9p/transport.h index 766ec07c9599..f0981515148d 100644 --- a/include/net/9p/transport.h +++ b/include/net/9p/transport.h @@ -24,6 +24,9 @@ * we're less flexible when choosing the response message * size in this case * @def: set if this transport should be considered the default + * @supports_vmalloc: set if this transport can work with vmalloc'd buffers + * (non-physically contiguous memory). Transports requiring + * DMA should leave this as false. * @create: member function to create a new connection on this transport * @close: member function to discard a connection on this transport * @request: member function to issue a request to the transport @@ -44,6 +47,7 @@ struct p9_trans_module { int maxsize; /* max message size of transport */ bool pooled_rbuffers; int def; /* this transport should be default */ + bool supports_vmalloc; /* can work with vmalloc'd buffers */ struct module *owner; int (*create)(struct p9_client *client, const char *devname, char *args); |