> From: Sasha Levin [mailto:levinsasha928@xxxxxxxxx] > Subject: Re: [PATCH v3 04/10] mm: frontswap: split out __frontswap_unuse_pages > > > > + assert_spin_locked(&swap_lock); > > > > Normally, we should use this assertion when we can't find swap_lock is hold or not easily > > by complicated call depth or unexpected use-case like general function. > > But I expect this function's caller is very limited, not complicated. > > Just comment write down isn't enough? > > Is there a reason not to do it though? Debugging a case where this > function is called without a swaplock and causes corruption won't be > easy. I'm not sure of the correct kernel style but I like the fact that assert_spin_locked both documents the lock requirement and tests it at runtime. I don't know the correct kernel syntax but is it possible to make this code be functional when the kernel "debug" option is on, but a no-op when "debug" is disabled? IMHO, that would be the ideal solution. > > > + for (type = swap_list.head; type >= 0; type = si->next) { > > > + si = swap_info[type]; > > > + si_frontswap_pages = atomic_read(&si->frontswap_pages); > > > + if (total_pages_to_unuse < si_frontswap_pages) { > > > + pages = pages_to_unuse = total_pages_to_unuse; > > > + } else { > > > + pages = si_frontswap_pages; > > > + pages_to_unuse = 0; /* unuse all */ > > > + } > > > + /* ensure there is enough RAM to fetch pages from frontswap */ > > > + if (security_vm_enough_memory_mm(current->mm, pages)) { > > > + ret = -ENOMEM; > > > > > > Nipick: > > I am not sure detailed error returning would be good. > > Caller doesn't matter it now but it can consider it in future. > > Hmm, > > Is there a reason to avoid returning a meaningful error when it's pretty > easy? I'm certainly not an expert on kernel style (as this whole series of patches demonstrates :-) but I think setting a meaningful error code is useful documentation and plans for future users that might use the error code. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href