Re: [PATCH v2] powerpc/eeh: Fix recursive locking on devices without EEH sensitive driver
From: Amit Machhiwal <hidden>
Date: 2026-07-15 10:16:49
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On 2026/07/14 05:16 PM, Shivaprasad G Bhat wrote:
The commit 1010b4c012b0 ("powerpc/eeh: Make EEH driver device hotplug
safe") refactored the EEH code such that the pci_rescan_remove_lock is
held at the beginning of eeh_handle_normal_event() and the
eeh_reset_device() is called with that lock being held. Looks like the
commit missed to remove the existing lock/unlock inside eeh_rmv_device()
which is no longer necessary. This is causing the eehd to hang on the
lock which it actually holds when that code path is taken.
[<0>] 0xc00000011c78f870
[<0>] __switch_to+0xfc/0x1a0
[<0>] pci_lock_rescan_remove+0x30/0x44
[<0>] eeh_rmv_device+0x290/0x2e0
[<0>] eeh_pe_dev_traverse+0x80/0x130
[<0>] eeh_reset_device+0xcc/0x23c
[<0>] eeh_handle_normal_event+0x830/0xa80
[<0>] eeh_event_handler+0xf8/0x190
[<0>] kthread+0x194/0x1b0
[<0>] start_kernel_thread+0x14/0x18
The issue is seen for cases where the errors are detected on the PHB
directly AND|OR for devices where the driver error_detected() returns
PCI_ERS_RESULT_NEED_RESET, and driver being not EEH sensitive(i.e no
error handlers like slot_reset(), resume() etc defined).
Fixes: 1010b4c012b0 ("powerpc/eeh: Make EEH driver device hotplug safe")
Cc: stable <stable@kernel.org>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Shivaprasad G Bhat <redacted>
---
arch/powerpc/kernel/eeh_driver.c | 2 --
1 file changed, 2 deletions(-)The change makes sense. eeh_handle_normal_event() already holds the rescan/remove lock across eeh_reset_device(), so taking it again in eeh_rmv_device() can deadlock exactly as described. Reviewed-by: Amit Machhiwal <redacted> Thanks, Amit
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c index 028f69158532..d64cce17a4e0 100644 --- a/arch/powerpc/kernel/eeh_driver.c +++ b/arch/powerpc/kernel/eeh_driver.c@@ -533,9 +533,7 @@ static void eeh_rmv_device(struct eeh_dev *edev, void *userdata) if (rmv_data) list_add(&edev->rmv_entry, &rmv_data->removed_vf_list); } else { - pci_lock_rescan_remove(); pci_stop_and_remove_bus_device(dev); - pci_unlock_rescan_remove(); } }