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mshv: Fix sleeping under spinlock in mshv_portid_alloc

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idr_alloc() is called with GFP_KERNEL inside idr_lock(), which holds a
spinlock. GFP_KERNEL allows the allocator to sleep, triggering a
sleeping-while-atomic bug.

Fix by using idr_preload(GFP_KERNEL) before taking the lock to
pre-allocate memory in a sleepable context, then idr_alloc() with
GFP_NOWAIT inside the spinlock-protected section.

Fixes: 621191d709 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs")
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Stanislav Kinsburskii 2026-05-07 15:43:59 +00:00 committed by Wei Liu
parent 649dd13549
commit a9708e550d
1 changed files with 4 additions and 2 deletions
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6
drivers/hv/mshv_portid_table.c
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@ -40,12 +40,14 @@ mshv_port_table_fini(void)
int
mshv_portid_alloc(struct port_table_info *info)
{
int ret = 0;
int ret;
idr_preload(GFP_KERNEL);
idr_lock(&port_table_idr);
ret = idr_alloc(&port_table_idr, info, PORTID_MIN,
PORTID_MAX, GFP_KERNEL);
PORTID_MAX, GFP_NOWAIT);
idr_unlock(&port_table_idr);
idr_preload_end();
return ret;
}