Kernels 5.4+ have an infinite retry loop from MAP_POPULATE mmap
option. Use the FAULT_FLAG_RETRY_NOWAIT to instruct filemap_fault
to not drop the mmap_sem so if the call fails, we could use
the slow path and break the loop from forming.
(Idea by Neil Brown)
Test-Parameters: testlist=sanity-hsm env=ONLY=1 clientdistro=ubuntu2004
Change-Id: I320ab9ca447282aea15ef2030ef8671c4260d895
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40221
Reviewed-by: Neil Brown <neilb@suse.de>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: Maloo <maloo@whamcloud.com>
if (ll_sbi_has_fast_read(ll_i2sbi(file_inode(vma->vm_file)))) {
/* do fast fault */
if (ll_sbi_has_fast_read(ll_i2sbi(file_inode(vma->vm_file)))) {
/* do fast fault */
+ bool has_retry = vmf->flags & FAULT_FLAG_RETRY_NOWAIT;
+
+ /* To avoid loops, instruct downstream to not drop mmap_sem */
+ vmf->flags |= FAULT_FLAG_RETRY_NOWAIT;
ll_cl_add(vma->vm_file, env, NULL, LCC_MMAP);
fault_ret = ll_filemap_fault(vma, vmf);
ll_cl_remove(vma->vm_file, env);
ll_cl_add(vma->vm_file, env, NULL, LCC_MMAP);
fault_ret = ll_filemap_fault(vma, vmf);
ll_cl_remove(vma->vm_file, env);
+ if (!has_retry)
+ vmf->flags &= ~FAULT_FLAG_RETRY_NOWAIT;
/* - If there is no error, then the page was found in cache and
* uptodate;
* - If VM_FAULT_RETRY is set, the page existed but failed to
/* - If there is no error, then the page was found in cache and
* uptodate;
* - If VM_FAULT_RETRY is set, the page existed but failed to
- * lock. It will return to kernel and retry;
+ * lock. We will try slow path to avoid loops.
* - Otherwise, it should try normal fault under DLM lock. */
* - Otherwise, it should try normal fault under DLM lock. */
- if ((fault_ret & VM_FAULT_RETRY) ||
+ if (!(fault_ret & VM_FAULT_RETRY) &&
!(fault_ret & VM_FAULT_ERROR))
GOTO(out, result = 0);
!(fault_ret & VM_FAULT_ERROR))
GOTO(out, result = 0);