* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [230927 13:14]: > On Wed, 27 Sep 2023 12:07:44 -0400 "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> wrote: > > > When merging of the previous VMA fails after the vma iterator has been > > moved to the previous entry, the vma iterator must be advanced to ensure > > the caller takes the correct action on the next vma iterator event. Fix > > this by adding a vma_next() call to the error path. > > > > Users may experience higher CPU usage, most likely in very low memory > > situations. > > Looking through this thread: > > > Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@xxxxxxxxxxxxxx/ > > I'm seeing no indication that the effect is CPU consumption? Jann is > excpecting bogus oom-killing? His testing injected a bogus oom, but since the vma iterator may get stuck in a "I can merge! oh, I'm out of memory" loop due to the vma_merge() called with the same VMA in this loop, I would expect it to be increased CPU usage when almost out of memory until a task is killed. I don't think he expected a bogus OOM since we are using GFP_KERNEL during mm/internal.h:vma_iter_prealloc() calls.
