Facebook and G.M. Said to Seek Solution to Fallout Over Advertising After a very public falling out in May, General Motors and Facebook may be ready to patch things up. According to a person with knowledge of the negotiations, senior executives from both companies - including Sheryl Sandberg, the chief operating officer for Facebook, and Daniel Akerson, the chief executive at General Motors - have been in discussions to mend their relationship. Carolyn Everson, the global head of sales for Facebook, and Joel Ewanick, the chief marketing officer for General Motors, met in Cannes, France, at the end of June, the person said. The conversation, held during the Cannes Lions International Festival of Creativity, an annual advertising conference, was the first face-to-face meeting the two companies had conducted since G.M. decided to end its paid advertising on Facebook, the person said. The news was first reported on Tuesday by the Wall Street Journal. The two companies are attempting to revive the relationship that soured in May when G.M., just several days before Facebook conducted its public offering, decided to discontinue its advertising on Facebook, suggesting the results did not justify the expense. The decision did not involve a large amount of revenue, but it became a public relations headache for Facebook, which has been trying to prove that advertising on the site is effective. Facebook reported $3.7 billion in revenue in 2011. G.M."s move also added to the uncertainty among advertisers who were trying to determine how to best use the site: continue to pay for advertising on Facebook or invest more in creating content - like videos - for branded pages. General Motors was spending roughly $10 million for paid ads on Facebook, but had invested an additional $30 million on managing and creating content for their pages. General Motors, is one of the world's largest advertisers, spending about $3 billion on advertising annually worldwide. The company has advertised on Facebook since 2008. Since the pullout, Facebook has been on a mission to prove to marketers that their ads are effective, including releasing a report in mid-June with the research firm comScore, which highlighted the successes that brands like Starbucks and Target had had on the site. Facebook has also made news on its own over the past few weeks including the acquisition of face.com, a facial recognition technology company. Facebook also announced it was encouraging companies to sell their products on Facebook using a payment system hat it had previously used for gaming. The company also announced it would begin testing a new advertising system using a technology called real-time bidding, which allows advertisers to place bids on ad space at specific times. Called Facebook Exchange, the new system would allow advertisers to use cookies in Web browsers to track users after they visit Facebook and show them ads based on their Web browsing habits. Tanzina Vega writes about advertising and digital media. Follow @tanzinavega on Twitter.