From: "Aneesh Kumar K.V" aneesh.kumar@linux.ibm.com Subject: mm/vunmap: add cond_resched() in vunmap_pmd_range
Like zap_pte_range add cond_resched so that we can avoid softlockups as reported below. On non-preemptible kernel with large I/O map region (like the one we get when using persistent memory with sector mode), an unmap of the namespace can report below softlockups.
22724.027334] watchdog: BUG: soft lockup - CPU#49 stuck for 23s! [ndctl:50777] NIP [c0000000000dc224] plpar_hcall+0x38/0x58 LR [c0000000000d8898] pSeries_lpar_hpte_invalidate+0x68/0xb0 Call Trace: [c0000004e87a7780] [c0000004fb197c00] 0xc0000004fb197c00 (unreliable) [c0000004e87a7810] [c00000000007f4e4] flush_hash_page+0x114/0x200 [c0000004e87a7890] [c0000000000833cc] hpte_need_flush+0x2dc/0x540 [c0000004e87a7950] [c0000000003f5798] vunmap_page_range+0x538/0x6f0 [c0000004e87a7a70] [c0000000003f76d0] free_unmap_vmap_area+0x30/0x70 [c0000004e87a7aa0] [c0000000003f7a6c] remove_vm_area+0xfc/0x140 [c0000004e87a7ad0] [c0000000003f7dd8] __vunmap+0x68/0x270 [c0000004e87a7b50] [c000000000079de4] __iounmap.part.0+0x34/0x60 [c0000004e87a7bb0] [c000000000376394] memunmap+0x54/0x70 [c0000004e87a7bd0] [c000000000881d7c] release_nodes+0x28c/0x300 [c0000004e87a7c40] [c00000000087a65c] device_release_driver_internal+0x16c/0x280 [c0000004e87a7c80] [c000000000876fc4] unbind_store+0x124/0x170 [c0000004e87a7cd0] [c000000000875be4] drv_attr_store+0x44/0x60 [c0000004e87a7cf0] [c00000000057c734] sysfs_kf_write+0x64/0x90 [c0000004e87a7d10] [c00000000057bc10] kernfs_fop_write+0x1b0/0x290 [c0000004e87a7d60] [c000000000488e6c] __vfs_write+0x3c/0x70 [c0000004e87a7d80] [c00000000048c868] vfs_write+0xd8/0x260 [c0000004e87a7dd0] [c00000000048ccac] ksys_write+0xdc/0x130 [c0000004e87a7e20] [c00000000000b588] system_call+0x5c/0x70
Link: http://lkml.kernel.org/r/20200807075933.310240-1-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Reported-by: Harish Sriram harish@linux.ibm.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/vmalloc.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/mm/vmalloc.c~mm-vunmap-add-cond_resched-in-vunmap_pmd_range +++ a/mm/vmalloc.c @@ -104,6 +104,8 @@ static void vunmap_pmd_range(pud_t *pud, if (pmd_none_or_clear_bad(pmd)) continue; vunmap_pte_range(pmd, addr, next, mask); + + cond_resched(); } while (pmd++, addr = next, addr != end); }
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