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net: introduce res_counter_charge_nofail() for socket allocations
There is a case in __sk_mem_schedule(), where an allocation is beyond the maximum, but yet we are allowed to proceed. It happens under the following condition: sk->sk_wmem_queued + size >= sk->sk_sndbuf The network code won't revert the allocation in this case, meaning that at some point later it'll try to do it. Since this is never communicated to the underlying res_counter code, there is an inbalance in res_counter uncharge operation. I see two ways of fixing this: 1) storing the information about those allocations somewhere in memcg, and then deducting from that first, before we start draining the res_counter, 2) providing a slightly different allocation function for the res_counter, that matches the original behavior of the network code more closely. I decided to go for #2 here, believing it to be more elegant, since #1 would require us to do basically that, but in a more obscure way. Signed-off-by: Glauber Costa <firstname.lastname@example.org> Cc: KAMEZAWA Hiroyuki <email@example.com> Cc: Johannes Weiner <firstname.lastname@example.org> Cc: Michal Hocko <email@example.com> CC: Tejun Heo <firstname.lastname@example.org> CC: Li Zefan <email@example.com> CC: Laurent Chavey <firstname.lastname@example.org> Acked-by: Tejun Heo <email@example.com> Signed-off-by: David S. Miller <firstname.lastname@example.org>
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