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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 4A8E820007 X-Stat-Signature: xpcwdns9wk1k4pd3p66hchqgif817dy7 X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1721633209-191336 X-HE-Meta: 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 BsHzx7mf Nv678jlnhEhWbTFmXm4JX8T5CNTbfQBDjR3Sk9mphojZtol8czCLWe9Xq+GBfIr/c3Lx9Is6tknxPvYPfOiXhqJST9FTsWZBIj7YwChRmFceV4CwpEX5I7Ubq1l8FuAhrFCiy373F2HcCZj/3jatsfR78e3ya/7ARcURzRn24Qy2eSsuNDvW63BUKtxD3kq1jP4s9GvyFMRDwnb/X0hTzcbMOYICuaVKzKB3/kqjS3MEDrTWiBFd7YSQ1ZUiM/yoZbFqbawA02RFTx4dINSF7/SnB7jL4/L+DzoXZEgPvbpWu/0vejQi6uK+hAo9NoU/M9D1mThJN9gc1a38Uy9n1hLNVMy00CoNjKH5SWznaMH98wb4TIJnxRrIo10L9wUyRBWsxEdgobkyQCHQoS6xwgJ/IonvwtqPe7hsuZ6BcS7HUXKo1UbAsxL0xRJqJz6QXPbOU3iTta86Gw2V/nF2Z9OKkB6Z3nNUq9/HLxB7PrlN6QcI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun 21-07-24 10:14:03, Barry Song wrote: > On Fri, Jul 19, 2024 at 7:53 PM Christoph Hellwig wrote: > > > > On Fri, Jul 19, 2024 at 07:43:38PM +1200, Barry Song wrote: > > > I doubt this is going to work as users can use a variant to save gfp_flags. > > > On the other hand, isn't it necessarily a bug of vdpa, why can't it be mm? > > > > > > if mm disallows GFP_NOFAIL, there must be a doc to say that; if it allows, > > > we should never return NULL. > > > > Yeah. Maybe the right answer is to have separate _nofail variants that > > don't take any flags and make GFP_NOFAIL an entirely mm-private internal > > flags that is rejected by all external interfaces. That should also > > really help with auditing the users. This would require duplicating many of our allocations APIs. > Just like Michal has consistently asserted that using GFP_NOFAIL with > non-wait is against the rules, I think we should enforce this policy by: > > diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h > index 313be4ad79fd..a5c09f9590f2 100644 > --- a/include/linux/gfp_types.h > +++ b/include/linux/gfp_types.h > @@ -258,7 +258,7 @@ enum { > #define __GFP_KSWAPD_RECLAIM ((__force gfp_t)___GFP_KSWAPD_RECLAIM) > /* kswapd can wake */ > #define __GFP_RECLAIM ((__force > gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM)) > #define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL) > -#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) > +#define __GFP_NOFAIL ((__force gfp_t)(___GFP_NOFAIL | ___GFP_DIRECT_RECLAIM)) > #define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) > > Anyone misusing GFP_ATOMIC | __GFP_NOFAIL in an atomic context > risks experiencing a crash due to sleep in atomic. This is a common > consequence, as all instances of sleep in atomic should result in the > same issue. I really dislike any of __GFP_$FOO to have side effects like this. Please let's not overdo this. -- Michal Hocko SUSE Labs