On Mon, Jun 11, 2012 at 10:27 AM, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> wrote: >> 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. The kernel style is to do " 3) Separate your changes. Separate _logical changes_ into a single patch file. " So it is fine, but it should be in its own patch. > > 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. Aye. -- 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