Rock stars are supposed to be abrasive. Dave Grohl is relentlessly friendly. Rock stars are supposed to be sullen. Dave Grohl loves to talk. Rock stars are supposed to be mysterious. Dave Grohl is a goof.

Rock stars are also supposed to be haunted. And that’s where the Foo Fighters singer-guitarist comes closest to fitting the bill — even if his wild, coffee-fueled laughter does plenty to mask it. The drummer-turned-frontman has spent the past 17 years trying to outrun the noisy, generation-defining smog of Nirvana, a band whose rapturous distortion will hang over rock-and-roll for as long as rock-and-roll continues to exist.

It was Grohl’s drumming that made Nirvana truly volcanic — those brute force thunderclaps rivaled John Bonham’s finest pummeling. And when it helped launch the band to unimaginable levels of fame, Grohl would often retreat to his mom’s house in Springfield. “If I ever felt like I was getting lost in the hurricane that was storming around Nirvana, I’d just go back to Virginia,” he says of his childhood home.

It was there that he learned of Cobain’s March 1994 drug overdose in Italy the same way we all did: watching MTV News. A month later, Cobain’s suicide in Seattle brought Nirvana to a devastating halt, and the best rock drummer alive didn’t want to play his drums anymore. Flooded by offers to join various bands, he batted them away. “It didn’t even register,” Grohl said in an interview last month at the South by Southwest music festival in Austin, Tex. “I just wanted to disappear for a while.”

So he booked a flight to Ireland and went road-tripping around the Ring of Kerry, searching for solitude in rolling emerald pastures. “It’s one of the most beautiful places on Earth,” Grohl says. “There’s nothing for miles.”

One afternoon, he was driving down a dirt road. He hadn’t seen a soul for hours. Suddenly, a hitchhiker appeared on the roadside. Grohl slowed down. Squinted. The hitchhiker was wearing a Kurt Cobain T-shirt.

Grohl kept on driving.

Fleeing the past

Now 42, Grohl is a hairier, beardier, tattooier version of the scrawny kid abusing his drum kit on MTV 20 years ago. (Twenty years ago!) He has a new documentary, “Foo Fighters: Back and Forth,” and the band’s seventh album, “Wasting Light,” comes out Tuesday.

And although Grohl is willing to revisit the past, he doesn’t want to spend a lot of time there.

“I remember reading an interview with [Washington punk legend] Ian MacKaye, where he was talking about nostalgia and how unproductive it can be,” Grohl says. “When there’s so much left to do, why spend your time focusing on things you’ve already done, counting trophies or telling stories about the good old days? And that really affected me, because he’s right. It’s the reason we started Foo Fighters. . . . We started it to [expletive] get away from the past. After Nirvana ended, it was the one thing healing us from the heartbreak of losing a friend and a band.”

In that sense, Foo Fighters are a therapy session that has lasted seven albums and counting. “I cannot forgive you, yet,” Grohl seethes on a new song called “I Should Have Known.” Is it about Cobain? Grohl says no. But it features a guest performance from Nirvana bassist Krist Novoselic and was produced by Butch Vig. The three hadn’t been in the same room since the recording sessions for Nirvana’s 1991 breakthrough “Nevermind.”

The album was recorded in Grohl’s garage in California’s San Fernando Valley so he could sneak out to the pool and take a dip with his daughter between takes. The album also sees the return of on-again, off-again Foo Fighter and Nirvana guitarist Pat Smear, who describes the “Wasting Light” sessions as “the easiest, nicest recording experience I ever had.”

The first Foo Fighters’ album was born out of a much tougher recording session in 1994, one in which Grohl scraped himself off the couch and forced himself into a Seattle recording studio. There, he made a demo on which he played every instrument and sang every lyric. He liked it enough to go ahead and release it as the Foo Fighters’ 1995 debut album. But he didn’t want to be a solo act, and he quickly filled out the band with Smear, bassist Nate Mendel and drummer William Goldsmith, formerly of the proto-emo band Sunny Day Real Estate.

When the media swarmed the band after its first rehearsal, Grohl was annoyed. “What the [expletive] would we have to talk about after one rehearsal other than the past?” he still wonders. “We don’t even have a silly tour anecdote yet.”

They’d soon have plenty. The documentary traces the Foo Fighters’ ceaseless touring and chapters of internal drama that you’d hardly expect from a band that looked as though its members were having so much fun in their spoofball music videos. There are falling-outs, betrayals, drug overdoses, quittings, firings — the works. (Grohl says he winced during a segment about how he rerecorded Goldsmith’s drum parts on the band’s second album, causing Goldsmith to quit the band and Grohl to earn the unshakable reputation as a control freak.)

He describes the band’s extended internal drama in a very Grohl-ish way, recapping the band’s highs and lows in an hyper-caffeinated, sing-songy voice: “Ha-ha-ha! Ha-ha-ha! Ha-ha-ha! Someone quits! Ha-ha-ha! Ha-ha-ha! Ha-ha-ha! Someone ODs!

‘Like my Woodstock’

Grohl knew he was famous on Christmas night 1991. He was in his mom’s living room at her annual holiday party, a cozy little get-together that would usually draw about two dozen family friends. “Nevermind” was racing up the charts, where it would soon dethrone Michael Jackson from the No. 1 spot and go on to sell more than 10 million copies.

“There were 150 people at that party in a house the size of a McDonald’s bathroom,” Grohl says. “I was like, ‘Oh no. Really? Is this what it’s going to be like?’ And my buddy Jimmy [was] drunk with a knife, saying, ‘If I don’t know you, get the [expletive] out of here right now!’”

His mother, Virginia Grohl, says she was always happy to have her son home between tours but could tell he was troubled by the turbulence surrounding Nirvana’s breakneck ascent. “It just didn’t seem like it was as much fun as it ought to be,” she says.

“In some ways, nothing had changed,” Grohl says of his retreats home. “I still mowed my mother’s lawn and raked the leaves and took out the trash. To be honest, it wasn’t much different than being a high school dropout without a job.”

Before he quit high school to pursue music, Grohl was a funny, energetic kid obsessed with the Beatles. His mother, a public school teacher at Jefferson High, would bring home one of the school’s portable record players on weekends to play the Beatles’ greatest-hits albums. By age 13, he had started his first band.

“There was a club called Treebeard’s that was off of Duke Street that had an open mike night,” Grohl says. “I was playing guitar, and we played ‘Suffragette City’ and ‘Start Me Up’ or whatever. It was horrible.”

On a family trip to Illinois in summer 1983, Grohl’s older cousin switched him on to punk rock — something that really clicked back home in July at a Dead Kennedys show on the National Mall. “There were cops on horses beating the [expletive] out of people. There were police helicopters. . . . To see [Dead Kennedys frontman] Jello Biafra come on and talk about ‘the great Klansman in the sky with the blinking red eyes’ as he pointed at the Washington Monument. . . . It was like my Woodstock.”

He quickly became a fixture in the local hard-core punk scene, lurking around the 9:30 Club and d.c. space, where he fell for the Northern Virginia band Scream. “When I saw the p.o. box [on Scream’s album cover] was in Bailey’s Crossroads, it was like finding out Little Richard lives down the street,” he says.

Grohl heard that the band was looking for a new drummer, aced the audition and dropped out of Annandale High School — his third stop after stints at Jefferson and Bishop Ireton — to go on tour.

“Honestly I thought it was a really good idea,” Virginia Grohl says of her son’s decision. “He didn’t find anything in school to really tap into, which was too bad. . . . Scream was going on a trip to Europe, and I thought, ‘I don’t know of any better education than that.’ ”

And it was Scream that would lead Grohl to Nirvana. When the band played Seattle in 1990, Cobain and Novoselic were in the crowd. When Scream broke up later that year, they gave him a call.

Wanting to connect

Whenever Grohl gets butterflies, he says he looks at two photos on his phone. One is a snapshot of him shaking hands with President Obama during a visit to the White House. The other is of Freddie Mercury performing for what appears to be 10 kerzillion screaming fans. What do Grohl, the frontman of Queen and the president of the United States have in common? A desire to connect with the masses, perhaps?

“My songwriting is like extending a hand to the listener,” Grohl says. “One of the greatest feelings is standing onstage singing a song like ‘Best of You’ or ‘[My] Hero’ or ‘Everlong’ and hearing 80,000 people sing it with you, for 80,000 different reasons.”

But that urge to write populist, one-size-fits-all rock anthems might seem strange coming from a guy raised in Washington’s dogmatic, fiercely independent punk scene. Grohl doesn’t see it that way.

“When I get on stage at Wembley Stadium, I still feel like I did playing the 9:30 Club,” he says. “It’s the same energy. It really is. Washington, D.C., and the music scene is the foundation of everything for me. . . . The most important thing is that you honor that musical integrity, whether you make music that sounds like ABBA or you make music that sounds like Void.”

The integrity of the new Foo Fighters album is steeped in its reflective mood. “I was basically writing about the experience of being surrounded by family and friends and Butch and consumed by memories,” Grohl says. “And doing it in my garage, there’s something full circle about that. After everything that we’ve been through, we’ve managed to take this band to a place that we never aspired to be.”

And if it got bigger, he wouldn’t mind.

“I’d love it if everyone knew one Foo Fighters song,” Grohl says. “Why the [expletive] not?”