Messages in this thread | | | From | Vitaly Wool <> | Date | Wed, 3 Jul 2019 07:53:32 +0200 | Subject | Re: [PATCH v2] mm/z3fold.c: Lock z3fold page before __SetPageMovable() |
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On Wed, Jul 3, 2019 at 12:24 AM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Tue, 2 Jul 2019 15:17:47 -0700 Henry Burns <henryburns@google.com> wrote: > > > > > > > + if (can_sleep) { > > > > > > + lock_page(page); > > > > > > + __SetPageMovable(page, pool->inode->i_mapping); > > > > > > + unlock_page(page); > > > > > > + } else { > > > > > > + if (!WARN_ON(!trylock_page(page))) { > > > > > > + __SetPageMovable(page, pool->inode->i_mapping); > > > > > > + unlock_page(page); > > > > > > + } else { > > > > > > + pr_err("Newly allocated z3fold page is locked\n"); > > > > > > + WARN_ON(1); > > The WARN_ON will have already warned in this case. > > But the whole idea of warning in this case may be undesirable. We KNOW > that the warning will sometimes trigger (yes?). So what's the point in > scaring users?
Well, normally a newly allocated page that we own should not be locked by someone else so this is worth a warning IMO. With that said, the else branch here appears to be redundant.
~Vitaly
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